Identity: A cryptographic tale

Identity? You want to use some online service... you put your email and a password... that's stored in some database.. Now every time you want to access the service you put in the same thing and you get access .. That email and password combination stored in a company's database is your identity for that service... That's the web2 world.. Where is the Problem? You don't own it...it's stored in some database It's centralized...if a company chooses to not allow you to use it you can't.. There is n