This is how I have set up the icon-links in my header.
<link rel="shortcut icon" type="image/x-icon" href="favicon.ico" />
<link rel="apple-touch-icon" href="apple-touch-icon.png">
<link rel="icon" type="image/png" href="/screen/favicon.png" sizes="192x192">
My 16x16 favicon.ico shows a simplified version of my logo, which looks much better than a downscaled version of a larger PNG. For the touch-icons on mobile devices I have created a 192x192 png of my original logo. Since I added that larger PNG to my header, it is not only used (correctly) as a touch-icon, but also replaces the 16x16 favicon.ico. Thus on the browsers the downscaled png-version is display. I dislike it, cause the ico-version looks better.
Is there any way, to force the display of the ico-version of my favicon in browsers?
If the reason of your high-resolution image/png icon is Android, then you should declare it via a web manifest.
This is what RealFaviconGenerator does: it only declares low-resolution image/png icons in the HTML. So desktop browsers only pick those, whereas Android get the high resolution icons it expects. Even if you don't plan to use the service, you can generate a fake set of icons and adapt the generated code and files to your needs.
Full disclosure: I'm the author of this service.
the last opened pages got a shortcut in chrome and safari on smartphone. but my page not.
how do I set up the picture for this?
for example ikea and bild works
favicon is set
<link rel="shortcut icon" href="include/designs/wirte/favicon.ico">
<link rel="shortcut icon" href="include/designs/design/images/favicon.png" type="image/x-icon">
<link rel="icon" href="include/designs/design/images/favicon.png" type="image/x-icon">
iOS Safari uses the Apple Touch icon for this purpose and also bookmarks and home screen icons. You definitely want to declare this one.
Android Chrome is similar, it reuses the icon it already takes for bookmarks and home screen icons:
A high resolution icon declared in a Web App manifest.
Else, a high resolution PNG icon.
Else, the classic Apple Touch icon.
As an alternative to the classic, manual creation, you can use this online favicon generator. It allows you to design your icons platform per platform and creates the icons and HTML you need to get the job done. Full disclosure: I'm the author of this site.
Add this code with your favicon.
<link rel="SHORTCUT ICON" HREF="/favicon.png">
I was reading the Favicon page on Wikipedia. They mention the HTML 5 spec for Favicon:
The current HTML5 specification recommends specifying size icons in multiple sizes using the attributes rel="icon" sizes="space-separated list of icon dimensions" within a tag. [source] Multiple icon formats, including container formats such as Microsoft .ico and Macintosh .icns files, as well as Scalable Vector Graphics may be provided by including the icon's content type in the form of type="file content-type" within the tag.
Looking at the cited article (W3) they show this example:
<link rel=icon href=favicon.png sizes="16x16" type="image/png">
<link rel=icon href=windows.ico sizes="32x32 48x48" type="image/vnd.microsoft.icon">
<link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768">
<link rel=icon href=iphone.png sizes="57x57" type="image/png">
<link rel=icon href=gnome.svg sizes="any" type="image/svg+xml">
My question is do any browsers support the HTML 5 method?
Note: I know Apple uses their apple-touch-icon meta tag method over the HTML5 method.
The wikipedia article claims:
The Google Chrome web browser however, will select the closest matching size from those provided in the HTML headers to create 128×128 pixel application icons when the user chooses the Create application shortcuts... from the "Tools" menu.
How does Internet Explorer (v9 to v11) and Firefox handle this? And is the article correct in how Chrome handles the HTML Favicons? (There is no source cited for Chrome confirming this.)
In searching I wasn't able to really find any (credible) info on HTML 5 Favicon other than the Wikipedia Article.
The answers provided (at the time of this post) are link only answers so I thought I would summarize the links into an answer and what I will be using.
When working to create Cross Browser Favicons (including touch icons) there are several things to consider.
The first (of course) is Internet Explorer. IE does not support PNG favicons until version 11. So our first line is a conditional comment for favicons in IE 9 and below:
<!--[if IE]><link rel="shortcut icon" href="path/to/favicon.ico"><![endif]-->
To cover the uses of the icon create it at 32x32 pixels. Notice the rel="shortcut icon" for IE to recognize the icon it needs the word shortcut which is not standard. Also we wrap the .ico favicon in a IE conditional comment because Chrome and Safari will use the .ico file if it is present, despite other options available, not what we would like.
The above covers IE up to IE 9. IE 11 accepts PNG favicons, however, IE 10 does not. Also IE 10 does not read conditional comments thus IE 10 won't show a favicon. With IE 11 and Edge available I don't see IE 10 in widespread use, so I ignore this browser.
For the rest of the browsers we are going to use the standard way to cite a favicon:
<link rel="icon" href="path/to/favicon.png">
This icon should be 196x196 pixels in size to cover all devices that may use this icon.
To cover touch icons on mobile devices we are going to use Apple's proprietary way to cite a touch icon:
<link rel="apple-touch-icon-precomposed" href="apple-touch-icon-precomposed.png">
Using rel="apple-touch-icon-precomposed" will not apply the reflective shine when bookmarked on iOS. To have iOS apply the shine use rel="apple-touch-icon". This icon should be sized to 180x180 pixels as that is the current size recommend by Apple for the latest iPhones and iPads. I have read Blackberry will also use rel="apple-touch-icon-precomposed".
As a note: Chrome for Android states:
The apple-touch-* are deprecated, and will be supported only for a short time. (Written as of beta for m31 of Chrome).
Custom Tiles for IE 11+ on Windows 8.1+
IE 11+ on Windows 8.1+ does offer a way to create pinned tiles for your site.
Microsoft recommends creating a few tiles at the following size:
Small: 128 x 128
Medium: 270 x 270
Wide: 558 x 270
Large: 558 x 558
These should be transparent images as we will define a color background next.
Once these images are created you should create an xml file called browserconfig.xml with the following code:
<?xml version="1.0" encoding="utf-8"?>
<browserconfig>
<msapplication>
<tile>
<square70x70logo src="images/smalltile.png"/>
<square150x150logo src="images/mediumtile.png"/>
<wide310x150logo src="images/widetile.png"/>
<square310x310logo src="images/largetile.png"/>
<TileColor>#009900</TileColor>
</tile>
</msapplication>
</browserconfig>
Save this xml file in the root of your site. When a site is pinned IE will look for this file. If you want to name the xml file something different or have it in a different location add this meta tag to the head:
<meta name="msapplication-config" content="path-to-browserconfig/custom-name.xml" />
For additional information on IE 11+ custom tiles and using the XML file visit Microsoft's website.
Putting it all together:
To put it all together the above code would look like this:
<!-- For IE 9 and below. ICO should be 32x32 pixels in size -->
<!--[if IE]><link rel="shortcut icon" href="path/to/favicon.ico"><![endif]-->
<!-- Touch Icons - iOS and Android 2.1+ 180x180 pixels in size. -->
<link rel="apple-touch-icon-precomposed" href="apple-touch-icon-precomposed.png">
<!-- Firefox, Chrome, Safari, IE 11+ and Opera. 196x196 pixels in size. -->
<link rel="icon" href="path/to/favicon.png">
Windows Phone Live Tiles
If a user is using a Windows Phone they can pin a website to the start screen of their phone. Unfortunately, when they do this it displays a screenshot of your phone, not a favicon (not even the MS specific code referenced above). To make a "Live Tile" for Windows Phone Users for your website one must use the following code:
Here are detailed instructions from Microsoft but here is a synopsis:
Step 1
Create a square image for your website, to support hi-res screens create it at 768x768 pixels in size.
Step 2
Add a hidden overlay of this image. Here is example code from Microsoft:
<div id="TileOverlay" onclick="ToggleTileOverlay()" style='background-color: Highlight; height: 100%; width: 100%; top: 0px; left: 0px; position: fixed; color: black; visibility: hidden'>
<img src="customtile.png" width="320" height="320" />
<div style='margin-top: 40px'>
Add text/graphic asking user to pin to start using the menu...
</div>
</div>
Step 3
You then can add thew following line to add a pin to start link:
Pin this site to your start screen
Microsoft recommends that you detect windows phone and only show that link to those users since it won't work for other users.
Step 4
Next you add some JS to toggle the overlay visibility
<script>
function ToggleTileOverlay() {
var newVisibility = (document.getElementById('TileOverlay').style.visibility == 'visible') ? 'hidden' : 'visible';
document.getElementById('TileOverlay').style.visibility = newVisibility;
}
</script>
Note on Sizes
I am using one size as every browser will scale down the image as necessary. I could add more HTML to specify multiple sizes if desired for those with a lower bandwidth but I am already compressing the PNG files heavily using TinyPNG and I find this unnecessary for my purposes. Also, according to philippe_b's answer Chrome and Firefox have bugs that cause the browser to load all sizes of icons. Using one large icon may be better than multiple smaller ones because of this.
Further Reading
For those who would like more details see the links below:
Wikipedia Article on Favicons
The Icon Handbook
Understand the Favicon by Jonathan T. Neal
rel="shortcut icon" considered harmful by Mathias Bynens
Everything you always wanted to know about touch icons by Mathias Bynens
No, not all browsers support the sizes attribute:
Safari: Yes, it picks the picture that fits best.
Opera: Yes, it picks the picture that fits best.
IE11: Not sure. It apparently takes the larger picture it finds, which is a bit crude but okay.
Chrome: No, see bugs 112941 and 324820. In fact, Chrome tends to load all declared icons, not only the best/first/last one.
Firefox: No, see bug 751712. Like Chrome, Firefox tends to load all declared icon.
Note that some platforms define specific sizes:
Android Chrome expects a 192x192 icon, but it favors the icons declared in manifest.json if it is present. Plus, Chrome uses the Apple Touch icon for bookmarks.
Coast by Opera expects a 228x228 icon.
Google TV expects a 96x96 icon.
I'd like to use a single image as both a regular favicon and iPhone/iPad friendly favicon.
Is this possible? Would an iPad-friendly 72×72 PNG scale if linked to as a regular browser favicon? Or do I have to use a separate 16×16 or 32×32 image?
Update for 2020: Sticking to the original question of 16x16 versus 32x32 icons: the current recommendation should be to provide a 32x32 icon, skipping 16x16 entirely. All current browsers and devices support 32x32 icons. The icon will routinely be upscaled to as much as 192x192 depending on the environment (assuming there are no larger sizes available or the system didn't recognize them). Upscaling from ultra low resolution has a noticeable effect so better stick to 32x32 as the smallest baseline.
For IE, Microsoft recommends 16x16, 32x32 and 48x48 packed in the favicon.ico file.
For iOS, Apple recommends specific file names and resolutions, at most 180x180 for latest devices running iOS 8.
Android Chrome primarily uses a manifest and also relies on the Apple touch icon.
IE 10 on Windows 8.0 requires PNG pictures and a background color and IE 11 on Windows 8.1 and 10 accepts several PNG pictures declared in a dedicated XML file called browserconfig.xml.
Safari for Mac OS X El Capitan introduces an SVG icon for pinned tabs.
Some other platforms look for PNG files with various resolutions, like the 96x96 picture for Google TV or the 228x228 picture for Opera Coast.
Look at this favicon pictures list for a complete reference.
TLDR: This favicon generator can generate all these files at once. The generator can also be implemented as a WordPress plugin. Full disclosure: I am the author of this site.
Short answer
The favicon is supposed to be a set of 16x16, 32x32 and 48x48 pictures in ICO format. ICO format is different than PNG. Non-square pictures are not supported.
To generate the favicon, for many reasons explained below, I advise you to use this favicon generator. Full disclosure: I'm the author of this site.
Long, comprehensive answer
Favicon must be square. Desktop browsers and Apple iOS do not support non-square icons.
The favicon is supported by several files:
A favicon.ico icon.
Some other PNG icons.
In order to get the best results across desktop browsers (Windows/IE, MacOS/Safari, etc.), you need to combine both types of icons.
favicon.ico
Although all desktop browsers can deal with this icon, it is primarily for older version of IE.
The ICO format is different of the PNG format. This point is tricky because some browsers are smart enough to process a PNG picture correctly,
even when it was wrongly renamed with an ICO extension.
An ICO file can contain several pictures and Microsoft recommends to put 16x16, 32x32 and 48x48 versions of the icon in favicon.ico.
For example, IE will use the 16x16 version for the address bar, and the 32x32 for a task bar shortcut.
Declare the favicon with:
<link rel="icon" href="/path/to/icons/favicon.ico">
However, it is recommended to place favicon.ico in the root directory of the web site and to not declare it at all and let the modern browsers pick the PNG icons.
PNG icons
Modern desktop browsers (IE11, recent versions of Chrome, Firefox...) prefer to use PNG icons. The usual expected sizes are 16x16, 32x32 and "as big as possible".
For example, MacOS/Safari uses the 196x196 icon if it is the biggest it can find.
What are the recommended sizes? Pick your favorite platforms:
Most desktop browsers: 16x16, 32x32, "as big as possible"
Android Chrome: 192x192
Google TV: 96x96
... and others that are more or less documented.
The PNG icons are declared with:
<link rel="icon" type="image/png" href="/path/to/icons/favicon-16x16.png" sizes="16x16">
<link rel="icon" type="image/png" href="/path/to/icons/favicon-32x32.png" sizes="32x32">
...
Beware: Firefox does not support the sizes attribute and uses the last PNG icon it finds. Make sure to declare the 32x32 picture last: it is good enough for Firefox, and that will prevent it from downloading a big picture it does not need. edit: fixed in 2016.
Also note that Chrome does not support the sizes attribute and tends to load all declared icons. Better not declare too many icons. edit: fixed in 2018.
Mobile platforms
This question is about desktop favicon so there is no need to delve too much in this topic.
Apple defines touch icon for the iOS platform.
iOS does not support non-square icon. It simply rescales non-square pictures to make them square (look for the Kioskea example).
Android Chrome relies on the Apple touch icon and also defines a 192x192 PNG icon.
Microsoft defines the tile picture and the browserconfig.xml file.
Conclusion
Generating a favicon that works everywhere is quite complex. I advise you to use this favicon generator. Full disclosure: I'm the author of this site.
I don't see any up to date info listed here, so here goes:
To answer this question now, 2 favicons will not do it if you want your icon to look great everywhere. See the sizes below:
16 x 16 – Standard size for browsers
24 x 24 – IE9 pinned site size for user interface
32 x 32 – IE new page tab, Windows 7+ taskbar button, Safari Reading List sidebar
48 x 48 – Windows site
57 x 57 – iPod touch, iPhone up to 3G
60 x 60 – iPhone touch up to iOS7
64 x 64 – Windows site, Safari Reader List sidebar in HiDPI/Retina
70 x 70 – Win 8.1 Metro tile
72 x 72 – iPad touch up to iOS6
76 x 76 – iOS7
96 x 96 – GoogleTV
114 x 114 – iPhone retina touch up to iOS6
120 x 120 – iPhone retina touch iOS7
128 x 128 – Chrome Web Store app, Android
144 x 144 – IE10 Metro tile for pinned site, iPad retina up to iOS6
150 x 150 – Win 8.1 Metro tile
152 x 152 – iPad retina touch iOS7
196 x 196 – Android Chrome
310 x 150 – Win 8.1 wide Metro tile
310 x 310 – Win 8.1 Metro tile
2021 standards thanks to faviconit
I use faviconit.com for the best browser and device support possible. You upload an image and this site gives you the code, the converted images and a browserconfig file.
We could simply upload a favicon manually to our website of 16x16 and it will probably show up in almost any browser.
But when you will mark it as one of your favorites on your smartphone or tablet, we will need larger images (60x60 to 144x144).
And lets say one of our users creates a shortcut on their desktop. In that case a 196x196 looks better!
Example code of what faviconit would give you, next to all the converted images:
<!-- place this in your <head></head> -->
<link rel="shortcut icon" href="/favicon.ico">
<link rel="icon" sizes="16x16 32x32 64x64" href="/favicon.ico">
<link rel="icon" type="image/png" sizes="196x196" href="/favicon-192.png">
<link rel="icon" type="image/png" sizes="160x160" href="/favicon-160.png">
<link rel="icon" type="image/png" sizes="96x96" href="/favicon-96.png">
<link rel="icon" type="image/png" sizes="64x64" href="/favicon-64.png">
<link rel="icon" type="image/png" sizes="32x32" href="/favicon-32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/favicon-16.png">
<link rel="apple-touch-icon" href="/favicon-57.png">
<link rel="apple-touch-icon" sizes="114x114" href="/favicon-114.png">
<link rel="apple-touch-icon" sizes="72x72" href="/favicon-72.png">
<link rel="apple-touch-icon" sizes="144x144" href="/favicon-144.png">
<link rel="apple-touch-icon" sizes="60x60" href="/favicon-60.png">
<link rel="apple-touch-icon" sizes="120x120" href="/favicon-120.png">
<link rel="apple-touch-icon" sizes="76x76" href="/favicon-76.png">
<link rel="apple-touch-icon" sizes="152x152" href="/favicon-152.png">
<link rel="apple-touch-icon" sizes="180x180" href="/favicon-180.png">
Since Windows 8
But that is not all. Since windows 8 we are able to create shortcuts to websites with tiles!
<!-- place this in your <head></head> -->
<meta name="msapplication-TileColor" content="#FFFFFF">
<meta name="msapplication-TileImage" content="/favicon-144.png">
<meta name="msapplication-config" content="/browserconfig.xml">
Browserconfig.xml
Upload a file named browserconfig.xml (to enable the tiles in windows >8)
<browserconfig>
<msapplication>
<tile>
<square70x70logo src="/favicon-70.png"/>
<square150x150logo src="/favicon-150.png"/>
<square310x310logo src="/favicon-310.png"/>
<TileColor>#FFFFFF</TileColor>
</tile>
</msapplication>
</browserconfig>
16x16 pixels, *.ico format.
I am not sure if/how browsers scale large icons, but The W3C suggests the following1:
The format for the image you have chosen must be 16x16 pixels or 32x32 pixels, using either 8-bit or 24-bit colors. The format of the image must be one of PNG (a W3C standard), GIF, or ICO.
1 w3c.org: How to Add a Favicon to your Site (Draft in development).
Actually, to make your favicon work in all browsers properly, you will have to add more than 10 files in the correct sizes and formats.
My friend and I have created an App just for this! you can find it in faviconit.com
We did this, so people don't have to create all these images and the correct tags by hand, create all of them used to annoy me a lot!
The simplest solution (2021)
Use one(!) SVG image
If you do not care about supporting Safari, you can use a single SVG icon:
<link rel="icon" href="favicon.svg" type="image/svg+xml" sizes="any">
Use one(!) PNG image
If you want full support*, you should add this to the head of your document:
<link rel="shortcut icon" type="image/png" href="/img/icon-192x192.png">
<link rel="shortcut icon" sizes="192x192" href="/img/icon-192x192.png">
<link rel="apple-touch-icon" href="/img/icon-192x192.png">
The last link is for Apple (home screen), the second one for Android (home screen) and the first one for the rest.
The size is exactly the size the Android home screen uses. The Apple home screen icon size is 60px (3x), so 180px and will be scaled down. Other platforms use the default shortcut icon, which will be scaled down too.
*Note that this solution does not support "tiles" in Windows 8/10. It does, however, support images in shortcuts, bookmarks and browser-tabs.
Wikipedia has this to say:
Additionally, such icon files can be
either 16×16 or 32×32 pixels in size,
and either 8-bit or 24-bit in color
depth (note that GIF files have a
limited, 256 color palette entries).
I think the best way is to use a 32x32 gif and test it with different browsers.
Simple solution for modern browsers (2022)
Use an SVG favicon:
<link rel="icon" href="/icon.svg">
Supported by major browsers (except Safari in 2021) and Living Standard
Only 1 short line of code and simple to remember
Other attributes like type and sizes are not necessary
Scales much better at any size compared to PNG
Let's end the favicon craziness with hundreds of different sizes...
You can have multiple sizes of icons in the same file. I routinely create favicons (.ico file) that are 48, 32, and 16 pixels. You can add in any size image you want. The question is, will the iPhone use an ico file?
ico also supports transparency, but I'm not sure if it's an alpha channel like PNG; probably more like GIF where it's on or it's off.
According to the Wikipedia Article on Favicon, Internet Explorer supports only the ICO format for favicons.
I would stick with two different icons.
As I learned, no one of those several solutions are perfects. Using a favicon generator is indeed a good solution but their number is overwhelming and it's hard to choose. I d'like to add that if you want your website to be PWA enabled, you need to provide also a 512x512 icon as stated by Google Devs :
icons including a 192px and a 512px version
I didn't met a lot of favicon generators enforcing that criteria (firebase does, but there is a lot of things it doesn't do). So the solution must be a mix of many other solutions.
I don't know, today at the begining of 2020 if providing a 16x16, 32x32 still relevant. I guess it still matters in certain context like, for example, if your users still use IE for some reason (this stills happen in some privates companies which doesn't migrate to a newer browser for some reasons)
No, you can't use a non-standard size or dimension, as it'd wreak havoc on peoples' browsers wherever the icons are displayed. You could make it 12x16 (with four pixels of white/transparent padding on the 12 pixel side) to preserve your aspect ratio, but you can't go bigger (well, you can, but the browser'll shrink it).
You will need separate files for each resolution I am afraid. There is a really good article on campaign monitor describing how they created and implemented their icons for each iOS device too:
http://www.campaignmonitor.com/blog/post/3234/designing-campaign-monitor-ios-icons/
The format of favicon must be square otherwise the browser will stretch it. Unfortunatelly, Internet Explorer < 11 do not support .gif, or .png filetypes, but only Microsoft's .ico format. You can use some "favicon generator" app like: http://favicon-generator.org/
favicon.ico is 16x16
<link rel="shortcut icon" href="favicon.ico"/>
And I use these ones to be beautiful in mobile and tablet:
<link rel="apple-touch-icon-precomposed" sizes="144x144" href="img/ico144.png">
<link rel="apple-touch-icon-precomposed" sizes="114x114" href="img/ico114.png">
<link rel="apple-touch-icon-precomposed" sizes="72x72" href="img/ico72.png">
<link rel="apple-touch-icon-precomposed" href="img/ico57.png">
It's important to use the name "favicon.ico" in the root because many browsers will try to find there first.
Seems like your file should be .ico type.
Check this post about favicons:
http://www.html-kit.com/support/favicon/image-size/
the format for the image you have chosen must be 16x16 pixels or
32x32 pixels, using either 8-bit or 24-bit colors. The format of the
image must be one of PNG (a W3C standard), GIF, or ICO. - How to Add a Favicon to your Site - QA # W3C
The favicon doesn't have to be 16x16 or 32x32. You can create a favicon that is 80x80 or 100x100, just make sure that both values are the same size, and obviously don't make it too large or too small, choose a reasonable size.
May I remind everybody that the question was:
I'd like to use a single image as both a regular favicon and iPhone/iPad friendly favicon? Is this possible? Would an iPad-friendly 72x72 PNG scale if linked to as a regular browser favicon? Or do I have to use a separate 16x16 or 32x32 image?
The answer is: YES, that is possible! YES, it will be scaled. NO, you do not need a 'regular browser favicon'. Please look at this answer: https://stackoverflow.com/a/48646940/2397550
This question already has answers here:
What is the best practice for creating a favicon on a web site? [closed]
(4 answers)
Closed 1 year ago.
What is currently the best way to get a favicon to display in all browsers that currently support it?
Please include:
Which image formats are supported by which browsers.
Which lines are needed in what places for the various browsers.
I go for a belt and braces approach here.
I create a 32x32 icon in both the .ico and .png formats called favicon.ico and favicon.png. The icon name doesn't really matter unless you are dealing with older browsers.
Place favicon.ico at your site root to support the older browsers (optional and only relevant for older browsers.
Place favicon.png in my images sub-directory (just to keep things tidy).
Add the following HTML inside the <head> element.
<link rel="icon" href="/images/favicon.png" type="image/png" />
<link rel="shortcut icon" href="/favicon.ico" />
Please note that:
The MIME type for .ico files was registered as image/vnd.microsoft.icon by the IANA.
Internet Explorer will ignore the type attribute for the shortcut icon relationship and this is the only browser to support this relationship, it doesn't need to be supplied.
Reference
I use .ico format and put the following two lines within the <head> element:
<link rel="icon" href="/favicon.ico" type="image/x-icon" />
<link rel="shortcut icon" href="/favicon.ico" type="image/x-icon" />
To also support touch icons for tablets and smartphones I prefer the approach of HTML5Boilerplate
More information on touch icons can be found in this article.
With the current status of browser-support you don't even have to add the HTML tag for the favicon in your document. The browsers will search automaticly a list of files, see this example for iOS:
If no icons are specified in the HTML, iOS Safari will search the
website’s root directory for icons with the apple-touch-icon or
apple-touch-icon-precomposed prefix. For example, if the appropriate
icon size for the device is 57 × 57 pixels, iOS searches for filenames
in the following order:
apple-touch-icon-57x57-precomposed.png
apple-touch-icon-57x57.png
apple-touch-icon-precomposed.png
apple-touch-icon.png
My advise is to not include a favicon in your document, but have a list of files ready in the root website:
apple-touch-icon-114x114-precomposed.png
apple-touch-icon-144x144-precomposed.png
apple-touch-icon-57x57-precomposed.png
apple-touch-icon-72x72-precomposed.png
apple-touch-icon-precomposed.png
apple-touch-icon.png (57px*57px)
favicon.ico HiDPI (32x32px)
When you download a template from html5boilerplate.com these are all included, you just have to replace them with your own icons.
Wikipedia to the rescue
IE6 cannot handle PNGs correctly, be warned.
Favicon must be an .ico file to work properly on all browsers.
Modern browsers also support PNG and GIF images.
I've found that in general the easiest way to create one is to use a freely available web service such as favicon.cc.
There is also a site where you can check how the favicon of any page is made
getfavicon.org
There you can see a tutorial about making favicons, image types and resolutions, it's nice!
Having a favicon.* in your root directory is automatically detected by most browsers. You can ensure it's detected by using:
<link rel="icon" type="image/png" href="/path/image.png" />
Personally I use .png images but most formats should work.
The answer to this question has become complicated enough that the best way is to just use a tool like RealFaviconGenerator, which lets you upload a png/jpg and then generates favicons and code to cover all the platforms for you: https://realfavicongenerator.net/