More Detailed Explanation on Michael Hartl's Tutorial - html

Question

In Michael Hartl's tutorial, it is written
<%= f.label :name %>
<%= f.text_field :name %>
it becomes
<label for="user_name">Name</label>
<input id="user_name" name="user[name]" type="text" />
and
<%= f.label :email %>
<%= f.email_field :email %>
becomes
<label for="user_email">Email</label>
<input id="user_email" name="user[email]" type="email" />
Was looking it for so long but I really could not understand how the code can translate to html. Can anyone explain?
These are all enclosed in the following code
<%= form_for(#user) do |f| %>
.
.
.
<% end %>

Answer 1

The label, <%= f.label :email %> is really just a method-call: You call form.label(:email). The <%= is short for <% print.
These methods are form-helpers, and included in the form object from FormHelper.
If you look at the code in the label method you'll see it instantiates a Tags::Label object.
Looking deeper at that Tags::Label it does a lot, but the most important part is the call to label_tag. Which renders a label tag.
The contents of the label tag is changed from :email to Email by using the humanize helper. (We ignore all the localisation and translation for now). You can use these helpers everywhere yourself. Open a console with rails console:
:email.to_s.humanize #=> "Email"
:postal_code.to_s.humanize #=> "Postal code"
In rails most of these stacks are hard to follow, because it is both abstracted into models (to allow re-use) and a lot of edge-cases such as localisation or XSS security mix in a lot of additional "cruft" that makes the path the code follows harder to understand.
But, in short, <%= f.label(:email) %> could roughly be translated to print label_tag(:email.to_s.humanize, id: :email).