If you manage a site, having a backup is something rather vital, particularly if you have important data or you have invested money and time in developing the site. There are numerous situations why you may require a backup - if you update a script and something goes wrong, if you eliminate a file or a whole folder by mistake, etc. Having regular backups will help you avoid any loss of information or at least minimize the damage, which is still better than losing the entire site. You'll be able to download a copy of your content on your desktop or notebook every now and then, but since you simply can't do that after every change, you'll have to rely on the backups that your web hosting provider generates. Because that is something very vital, you must ensure that they keep up-to-date backups, given that a backup created once every one or two weeks might not do any good if you run a site such as an online store or an accommodation booking website.