If you installed your wiki on a server owned by a hosting provider, then odds are it will be backed up for you every night. Should something happen to the server, there will always be a recent copy of your site on file with the company so they can easily restore the site; often times your provider will do this for you.
However, it is always good practice to back up your sites on your own instead of relying on someone else to do it for you. Before we begin, we need to take a look at how everything is stored in our wiki. MediaWiki stores important data in two locations:
The database where pages and their contents, users and their preferences, metadata, search index, and so on are stored
The filesystem where software configuration files, custom skins, extensions, images (including deleted images), and so on are stored
So if you are ready, let's step into the next couple of exercises where you will learn how to back up both your database and your wiki's filesystem.