All of the text in posts and pages on a WordPress site is stored in a database which is backed up every night. Each nightly database backup is stored for 7 days.
All images, files, the wordpress core, themes and plugins are synchronized to our backup system on a nightly basis.
We will also take a server snapshot prior to every maintenance update. The server snapshot makes it so that we can restore the entire server to exact state that it was in before making any updates.