A “cookie” is a small text file that is stored on your computer when you visit a website.
A “session cookie” is deleted when you close your browser. “Persistant cookies” remain on your device until they expire or you delete them from your browser. These kind of cookies help the website to remember information such as login details for returning visitors to the site.
For more information about cookies and how to manage them, visit http://www.allaboutcookies.org. You can also search for more information by using your favourite search engine.