I\'m creating a web app that requires registration/authentication, and I\'m considering using an email address as the sole user id. Here are what I see as the pros and cons (upd
If you don't care about forcing your users to login to your application with Facebook or some other social network (most people don't seem to care), then you can just use their social network email as their 'user id' when referencing other tables/documents (MySQL, Mongo, etc).
I've noticed the bonus to using social media logins is that all the security has been taken care of by said social network, including not allowing 2 users to have the same email or username in their database thus saving you the hassle of having to code for all of that. This is just my personal preference.
PRO
People hate having to create a unique name that fits their id and that has not already been taken to register for a site..So this is why the user id as EMAIL ADDRESS is so embraced.
ex:TStamper1930, who actually wants to remember 1930 at the end of my name that I really wanted
As a user of websites, I can tell you that I hate memorizing unnecessary usernames. I don't use a unique handle or anything so I can never remember which variation of my name I used that wasn't already taken. I'd much rather type my email address.
Also, I like OpenID.