cryptozombies LESSON 1 CHAPTER 13. can not understand the events in cryptozombies - ethereum

Question

I am learning solidity in cryptozombies. I just finished 12 chapters with the good understanding. but, I don't understand the events concept. I want to understand the full code. can somebody help me with that??
pragma solidity >=0.5.0 <0.6.0;
contract ZombieFactory {
event NewZombie(uint zombieId, string name, uint dna);
uint dnaDigits = 16;
uint dnaModulus = 10 ** dnaDigits;
struct Zombie {
string name;
uint dna;
}
Zombie[] public zombies;
function _createZombie(string memory _name, uint _dna) private {
uint id = zombies.push(Zombie(_name, _dna)) - 1;
emit NewZombie(id, _name, _dna);
}
function _generateRandomDna(string memory _str) private view returns (uint) {
uint rand = uint(keccak256(abi.encodePacked(_str)));
return rand % dnaModulus;
}
function createRandomZombie(string memory _name) public {
uint randDna = _generateRandomDna(_name);
_createZombie(_name, randDna);
}
}

Answer 1

The function of the event is that when the caller invokes this function, an additional logs will be added to the transaction content.
For a common example of ERC20 tokens, if the contract creator didn't add the event function when writing the Transfer function, something interesting would happen, the blockchain browser would not display the number of Hodlers properly and it would not show the detailed transaction history of the user-user transfer of ERC20 tokens.
Let's conclude that adding the event function will make it easier for the searcher on the blockchain browser to understand or analyze each transaction, but it will also make it easier for the searcher on the blockchain to find transactions or filter them for some arbitrage :)

Answer 2

Think of Events as the code piece that you put in a place where you want to be notified instantly if something happens there.
contract test{
function Alert() public returns (string memory) {
string memory str = "Alert! Do Something.";
return str;
}
}
for example in this code here you would want to be notified on your end-user screen so in order to that you would want your front-end to be able to get this info! right? and how would you go about doing that? by creating an event with which your front-end can interact with (particularly read from). Therefore you would modify the above code to add event to this as follows:
contract test{
event readAlert(string str);
function Alert() public returns (string memory) {
string memory str = "Alert! Do Something.";
return str;
emit readAlert(str);
}
}
After doing this you can now use the event you just created to do something with the info passed to it on you app front-end.
Let me know if you need further explanation. :)