Almost everyone has gone through this – a registration form that requires you to type an email or password twice. Personally, I find it pointless and annoying. This method was designed to prevent mistyping errors, which is understandable, considering users cannot see what they are typing in. Password field is masked for for security reasons, so that snoopers can’t see them. It is assumed when the user types it twice the chances of a mistake is smaller.

But is it? I like the view (and I agree with it) posted in the article by Smashing Magazine, quoted below.

The articles is worth a proper browse as it includes other valuable UX tips regarding simplifying log-in and sign-up forms.