In his book book Designing for Social Web Joshua Porter broadly classifies the stages through which users pass in the usage lifecycle of a software. The five stages starting at being 'unaware' to becoming a 'Passionate user' can be attributed to user engagement with sites as well. From not knowing much about what is being offered, to becoming a avid user, relying on the site and feeling confident using it - users unknowingly pass through these stages. The five stages mentioned are : Unaware, interested, first time user, regular user and passionate user.
From a user perspective, this is the most critical step, as sites often require users to enter secure and confidential information. Lack of trust and fear of spamming are the main reasons which hold users from signing in.
Pocket 's 'Sign-up' screen has a immediate appeal for being simple yet efficient. Only three clearly labelled fields, which no need to confirm email or password. This is the best 'sign-up' I have seen in some time. Twitter 'sign-up' is also similar asking user to enter only three details. The only reason I rate this better than twitter is, the label 'Full Name' is often confusing for user. For most user, full name would mean they need to enter a prefix, first name and last name. Years of experience in filling out forms in the web has thought most users a blank space in a form often returns a error message. Besides, there is the issue of middle name being a part of the full name. So the term 'full name' is not as simple as it sounds. 'Pocket' approach of asking for a 'username' is less confusing and as most web users have adopted a user name they use for on-line applications, this is more convenient.