«- Memory Alpha: Policies and Guidelines
As a general rule, it's important that users log in when making changes, because the changes can then be attributed to your username. You'll find that regular contributors are generally more suspicious and more critical of edits that are made anonymously.
But more than just assigning credit, logging in is important so that others can contact you if they have concerns, questions, or compliments concerning an article you wrote. Logging in helps to build the team, and helps others come to trust your contributions.
Anyone can create a username and maintain their account on Memory Alpha, and remain completely anonymous — you don't have to provide your real name, e-mail address, or other information.