A PHP Session persist the user information to be used later. For example, user name, password, shopping item details. The session is temporary and will be removed soon after the user has left the web site. The session can be persisted for long term usage on databases like MySQL. Each session is identified by a unique Id number for every visitor. The first step to use PHP session is to start the session. The starting session must precede the operations like HTML or the other.
The statement session_start() starts the PHP session and registers the user’s information on the server.
There is a decent page in the php manual on the subject, in short mysql_pconnect() makes a persevering association with the database which implies a SQL join that don't close when the execution of your script closes. mysql_connect()provides just for the database new association while utilizing mysql_pconnect , the capacity would first attempt to locate a (relentless) connection that is as of now open with the same host, username and password. On the off chance that one is found, an identifier for it will be returned as opposed to opening another connection... the connection with the SQL server won't be terminated when the execution of the script ends. Rather, the link will stay open for future use.
The principle distinction amongst sessions and cookies is that sessions are put away on the server, and cookies are put away on the client's PCs in the content record position. Cookies can not hold various variables,But Session can hold numerous variables.We can set expiry for a cookie,The session just stays dynamic the length of the program is open.Users don't have admittance to the information you put away in Session,Since it is put away in the server. Session is mostly utilized for login/logout reason while cookies utilizing for client movement following.