Keeps you signed in, protects forms against cross-site request forgery, and remembers your answers while you are part way through a test. Without these the site does not work, so they cannot be switched off.

Tells us which pages and which tests people actually use, and where they stop. Used to improve the site, never to identify you individually.

Lets Google, Meta and Microsoft measure which of their ads brought you here, and show you ours elsewhere. Turning this off does not mean fewer ads — only less relevant ones.