PHPMailer: Don't understand the from address - php

Question

I'm trying to learn PHPMailer and I don't understand why it needs an email address and password.
$mail->isSMTP(); // Set mailer to use SMTP
$mail->Host = 'smtp1.example.com;smtp2.example.com'; // Specify main and backup SMTP servers
$mail->SMTPAuth = true; // Enable SMTP authentication
$mail->Username = 'user#example.com'; // SMTP username
$mail->Password = 'secret'; // SMTP password
$mail->SMTPSecure = 'tls'; // Enable TLS encryption, `ssl` also accepted
$mail->Port = 587; // TCP port to connect to
It's not coming from a persons email, it's coming from the site. What email am I supposed to put here and why?

Answer 1

The email address is the address which the emails are sent from. The username and password are required for SMTP servers that require authentication in order to send mail.

Answer 2

The way email works is that party 1 has an email account which it uses to send mail to party 2. Party 1 can be a site, a person, a script or something else, but it still needs to have an email account to be able to send email.
This is the way SMTP (Simple Mail Transfer Protocol) has been defined, and you need to follow the definitions of that protocol to get your mail delivered.

Answer 3

It is not necessary to provide password -
<?php
require("class.phpmailer.php");
$mail = new PHPMailer();
$mail->IsSMTP(); // telling the class to use SMTP
$mail->Host = "smtp.example.com"; // SMTP server
$mail->From = "example#gmail.com";
$mail->AddAddress("example#gmail.com");
$mail->Subject = "First PHPMailer Message";
$mail->Body = "Hi! \n\n This is my first e-mail sent through PHPMailer.";
$mail->WordWrap = 50;
if(!$mail->Send()) {
echo 'Message was not sent.';
echo 'Mailer error: ' . $mail->ErrorInfo;
} else {
echo 'Message has been sent.';
}
?>
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