A MAC or Macro virus is a computer virus that spreads to other computers through software programs that utilize macros. For example, Microsoft Word and Microsoft Excel are two popular and widely used programs that are capable of executing macros. Macro viruses written for these programs can spread by infecting other related documents each time the document is open. Because these files are commonly used and sent through e-mail, a computer network can be quickly infected by these viruses.
The first macro virus was named Concept, accidentally released on the Microsoft Compatibility Test CD released by Microsoft. Discovered in July 1995, Concept was spread through e-mails having Microsoft Word documents attached to them. It infected Microsoft Word 6.0 and Microsoft Word 95 documents when they were saved using the Save As option. Luckily, Concept did not pose any danger and only displayed a message on the computer screen.