Once you signup you will be sent an email with a link to a unique url to go confirm it, such as CipherSanctum.com/email_signup_app/1/ycgj23-vqrt7ner-t2tu-ea4tbs-ad3tuij0811dr/
I'll bet you've seen urls like that many places before. Well in the database, every item inserted has an id that increments by 1 automatically. In the example above, the id is 1 because of the ...com/email_signup_app/1/... After that I have something called a Universal Unique ID added to it. The purpose of it is so random people can't go to CipherSanctum.com/email_signup_app/1/, 2, 3, 4, 5, etc., guess the emails, and confirm them.
Without that UUID, anyone could confirm or delete an entire email list very easily by starting at 1 and going until all emails are all confirmed, or entirely gone. This UUID makes it nearly impossible to do so, because they'd have to guess over 48,800,000,000,000,000,000,000,000,000,000,000,000,000,000,000 combinations. So they're one way of protecting data.