Is there such a thing as a unique browser $_SESSION id?

Question

I am working on add to favorites add-on (where posts will be added to favorites by signed in users), but then I saw that craigslist lets anyone add favorites without them being signed in. How do they do that? Is there a unique $_SESSION id for a browser? Sorry if it's a silly question.

As an example: http://orlando.craigslist.org/search/jjj (Click on any star to add to favorites. May not be available in IE 11).

Answer 1

他们只是在使用一个会话，您应该可以通过查看它们存储在计算机上的cookie来进行检查。

Answer 2

Everything in $_SESSION persist only for the current session. If the users closes the browser and reopen it a new session is generated. So $_SESSION is not the right place for your answer.

There is $_ENV where you can get the clients ip address and general browser data from. In most cases this is enough to identify a single user. If you keep track of these data you can prevent users from giving multiple votes.