In 1991, Symantec released the first version of Norton AntiVirus. Norton was a popular brand name among computer technophiles from the well-known and successful Norton Utilities program. Programs like Norton AntiVirus are designed to find and eliminate viruses from a computer, usually with three goals in mind:
- Make the virus stop doing harm to the computer it has infected
- Stop the spread of the virus
- Limit any further harm the virus can do
Early antivirus programs had a database that contained information about each known virus. Chiefly, the database would contain some of the characters that were found in each known virus. Then, as the antivirus program scanned files on the computer, it would simply compare the information in the scanned files with the information about each known virus. When there was a match, the antivirus program had found a virus.
Norton VirusScan was the first antivirus program available. It contained signatures for only several dozen viruses. In those days (reckoned by our sundials and hourglasses) it was sufficient to update signatures every few months. These early programs had no “real-time” detection mechanism; instead, they could only scan a computer to look for viruses that were already present on the computer.