Cookie - small piece of information that scripts can store on a client-side machine
Set-Cookie: name=value; [expires=date;] [path=path;] [domain=domain_name;] [secure;] [HttpOnly]
bool setcookie(string name [,string val [,int expire=0 [,string path [,string domain [,int secure=false] [,int httponly=false] ]]]])

setcookie('mycookie','value');

Session - session ID cookie stored on client-side machine, server-side session variables are stored with relation to session ID
1) Start session 2) SET session vars 3) Use session vars 4) UNSET session vars and destroy session
session_start()
$_SESSION['myvar'] = 5;
if(isset($_SESSION['myvar'])){//session and var is set}
unset($_SESSION['myvar']); or $_SESSION = array();
session_destroy();