What's the difference between disk and memory?

Can you go into more detail about what sticky settings are? 

Why didn't Flasks digital signature prevent me from tampering with the number of prior visits cookie in the cookie example webpage?

You mentioned in the reading that session identifiers are created at the start of a Flask session, but sessions do not have ""Session ID""s.  What is the difference between session IDs and session identifiers?

Why don't you need to worry about session files accumulating on the server and deleting old session files from the server?  Are session cookies not saved on the server?

If you clear browser cookies, could that end sessions running for websites? Are all logins made possible through sessions or are there other methods?

"Not a content question, but when I tried to click on the 'Session Secrets' link I got this message:

Internal Server Error: Missing headers or other script malfunction. Check the logs or contact cs-sysadmin@wellesley.edu"