This is useful only for files you won't be altering later. Backup Make multiple copies of important data often. The more important the files are, the more copies in more places you need. Antivirus Use an anitvirus program regularly. Computer viruses are sneaky computer programs that can erase your data and even your whole system.
Most viruses are merely annoying and are created as practical jokes.
But there are a number of very damaging viruses out there. Your computer gets a virus by downloading an infected file from the internet or your office network, or by first using a floppy in an infected computer and then accessing a file on that floppy with your own computer. This makes it difficult to keep a virus from spreading. Once you have disinfected your computer, it can get re-infected from a floppy that was used between the time you were infected with the virus and when you disinfected it. A number of nasty viruses hide for quite a while before doing their nasty things.