Signing in on a website ? how does the server manage it?

I am developing a site where access to certain pages might require the user to sign in. (he/she writes his username and password)

if the user has successfully signed in he/she can then access this pages.

How does the server know that this is the case ?

Does it figure the IP address o开发者_C百科f the sender when he/she establish the connection ? Does it set up a timeout variable on its side so to say: 'you have been disconnected because your activity was idle for 10 minutes' ???

Many websites have this abilities on I just don't know how this is done.

Can somebody explain ?

Thanks,

The most common solution is to use cookies. You could store session data or unique identifiers in the cookies, then your app would check the contents during each request.