Backup

A backup of a website is a copy of its content, that is kept on a different server and may be restored if something happens. This function is quite efficient, considering that you cannot know if a script update will not crash or if you will not delete something by mistake - a file, a folder, a database entry, etc. When your site is backed up, it may be restored the way it was before the issue appeared, so there shall not be any damage, or at least it will be minimal, based on the specific case. Keeping backups on your computer system is not very feasible, because you would need to do it at least once every day and you could still lose info if your last backup is not recent enough. In this light, you'll have to rely on your hosting company, so you must double-check their policy on the backups, given that some companies create backups just once per week, which will do no good if a problem occurs with a site which is being used and updated constantly, such as an online store, for example.