Software Update
Apply an update package to this site. Your current files are backed up automatically, so the last update can be undone if something goes wrong. Only the site owner can do this.
Apply an update
Choose the update package you were given (a .zip file). You can preview what it will change before applying it.
Database updates
Some updates change how the site stores its information. Check whether any are waiting, then apply them. Make sure you have a recent backup first.