Post status allows users to set a workflow status for a post in WordPress. There are 8 default statuses that WordPress uses. They are published, future, draft, pending, trash, auto-draft, and inherit. A post may also have a “new” status if it was just created and hasn’t had any previous status. WordPress themes and plugins can also define custom post statuses for more complex websites. These statuses allows users to organize their posts in the admin panel. They are especially useful for sites with multiple authors or a complicated editorial process.
Some things that post status allows is for users to work on an article without publishing it and saving it as a draft. This way they can go back later and finish it. It also allows users to schedule posts which gives the post a status of “future”, or make a post private. Attachments have a post status of “inherit”. For multi author blogs the “pending” status can be useful as contributors can submit posts for review prior to publishing.
It is expected that in the future versions of WordPress there will be more editorial controls added into the post-status functionality. Right now users can extend this functionality by using plugins, such as Edit Flow.