A backup is a copy of a site that's kept on another hosting server and can be restored if something wrong happens with the live Internet site - a failed script update, an accidental deletion of some file or of your whole database, and so on. Restoring the site the way it was shall remove or lessen the damage the problem may have caused, which is by all means a much better alternative than having to rebuild your whole website from scratch. While you could download a copy of your content on your laptop or computer, keeping a backup is a feature that nearly all website hosting companies offer as part of their plans. You have to check how often they do that, though, because some service providers generate a backup only once every 7 days, which may be far from enough for a booking website or an e-commerce portal in which the data is updated every single day. It's adviseable to see how fast and easy a backup may be restored, which can be vital if some problem appears on your site.