A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer. Each time the same computer requests a page with a browser, it will send the cookie too. With PHP, you can both create and retrieve cookie values.
How to create the cookie :-
The setcookie() function is used to set a cookie.
Note: The setcookie() function must appear BEFORE the <html> tag.
setcookie(name, value, expire, path, domain);