Help:Why create an account?
If you create an account, you can pick a username. Edits can only be make while logged in. Edits will be assigned to your name. That means you get full credit for your contributions in the page history. You can also view all your contributions by clicking the "My contributions" link, which is visible only when you are logged in.
You will have your own user page where you can write a bit about yourself. While PGVWiki is not a homepage provider, you can use this to display a few pictures, write about your hobbies, etc. What this page is used for is up to you.
You will have a permanent 'user talk page' you can use to communicate with other users. You will be notified whenever someone writes a message on your talk page. If you choose to give an e-mail address, other users will be able to contact you by e-mail. This feature is 'anonymous'; the user who emails you will not know your e-mail address.