If you're not registered, you're what we call a "cookie type user". And with that, your account only stays with you so long as your cookie remains.

If you wipe your cookies off your machine, or you want to use the site under your account from another PC, then you're effectively starting from scratch. And that means having to collect rep all over again to do the extra fun things on the site (i.e. comment, upvote, downvote).

That user will still be there, but you'll lose control over it. You can always ask us (ron.gross@gmail.com) to get it back, but it's easier to just register. Also, if you provided us with your email, you can reset your cookie via email.

Registering allows you to easily sign in and out from any computer you want.

If you also want to use the site through another browser, you can do that as well, but only if you're registered.

Remember the first day you were on the site, had only 1 rep and couldn't vote on anything? You also couldn't comment on a question asking for clarification, lest you did it in an answer and be thrashed by people flagging your post as spam?

Registering means you don't have to go through that kerfuffle more than once.