It makes a Second Copy of your data files to another directory, disk or computer across the network. It then monitors the source files and keeps the Second Copy updated with new or changed files. It runs in the background with no user interaction. So, once it is setup you always have a Second Copy of your data some where else. This sites been around a long time, and they do a great job.
Software is rated, and easy to find, but some days the site seems a little slow.
Literally hundreds of programs are available. You get mainframe quality tech support, and the best tools all from one source. Well organized, and fast. However, you may have to wade through a ton of end user software before you get to applications that you may actually find useful. NT Shareware One of our favorite sites.