A backup is a copy of a site that is kept on a different server and could be restored if something goes wrong with the live Internet site - a defeated script update, an accidental deletion of a file or of your whole database, etc. Restoring the site the way it was will eradicate or lessen the damage the problem may have caused, that 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 personal computer, keeping a backup is a feature that nearly all web hosting companies include as part of their packages. It is important to take a look at how frequently they do that, though, because some companies create a backup only once every few days, which might be far from enough for a booking Internet site or an e-commerce portal in which the info is updated every day. It's adviseable to see how fast and easy a backup could be restored, which can be crucial if some issue appears on your website.