What are cookies? They're parcels of text sent back and forth between your browser and the server you are accessing. Usually used for authentication and other user information needed by the server.
A Moodle server may send you two types of cookies.
- MoodleSession - essential, necessary to maintain login from page to page. It is destroyed when you log out or close the browser.
- MOODLEID - not essential, safe to refuse, just for convenience. It remembers your username within the browser. When you return to the page, the username in the login page will be filled.
Why is it needed in moodle? For interactivity and functionality. It is also required in certain modules like when you display a secure window in quizzes, or use a timer.
To accept cookies click Privacy and under Cookies check Accept cookies from sites.
Here's a screenshot of the entire process: