WordPress allows a site administrator to assign different levels of access to different people. For some people, the administrator may choose to grant almost unlimited powers: the power to add or edit content, delete posts from other users, and even change the access level granted to others.
For other people, the administrator may simply wish to allow them to read the site. For still others, the administrator may wish to grant them the ability to post and edit their own—but not someone else’s—posts. This level of access is called the “contributor” role.
A user who has been designated as a contributor can add to the site. That is, he or she may post and edit his or her own content. However, he or she cannot edit the content added by any other party.
The varying levels of control that an administrator can grant to other users is one of the features that makes WordPress so flexible. By recognizing that different people can contribute to a site, and yet not all of those people need unfettered access, WordPress helps administrators keep their sites running smoothly. At the same time, it acts to protect sites from what could happen if all users were given absolute free reign.