I logged into an online forum created by using PHP and was browsing some topics in the web site.
Since the weather was hot, I got to have a bath and left my computer idle for a short while.
When I came back to my computer, I pressed a "Add Post" icon.
But When I pressed to submit the new topic,the web site redirected me to the Log in page,
I gussed my cookie might have been expired. And then after I logged into the web site again,
my new post was created. I am wondering how they do this.
What is the method and technique they used?

Onlar benim cookie süresi olduğunu bulduğumda önce yeni bir kurabiye ya da bir oturuma yeni görevime saklamak mı?