The various account types dictate what a user is allowed to do on the site. Choose the appropriate role for the specific permissions a user should have.
Administrator: Nothing is off limits.
Editor: Has access to all posts, pages, comments, categories, tags, and links.
Author: Can write, upload photos to, edit, and publish their own posts.
Contributor: Has no publishing or uploading capability, but can write and edit their own posts until they are published.
Subscriber: Gives user a login to your website with no privileges, but means they can view Private pages if they are logged in – for example, for a private board member page.