Used for authentication after login. This holds the necessary data to (re)login a previously authenticated user.
Importance: necessary for anyone who needs to log in
Typical content: encrypted username and password
Expires: in a year 1)
Used for remembering helpful user preferences, like the size of the editor textarea.
Typical content: name/value pairs in plain text
Expires: in a year
The standard PHP session identifier. Used to hold temporary data and to avoid CSRF attacks.
Typical content: random ID
Expires: at the end of the browser session