Answer Description
A virus is a type of malware that infects another program (typically an exe/executable) and has the ability to spread itself to other systems. Both viruses and worms may have the ability to replicate themselves with or without user intervention. They key difference is that a worm is a standalone program while a virus infects an existing program, for example a critical Windows executable.
Wikipedia
A computer virus is a type of computer program that, when executed, replicates itself by modifying other computer programs and inserting its own code When this replication succeeds, the affected areas are then said to be "infected" with a computer virusComputer viruses cause billions of dollars' worth of economic damage each year,In 1989 The ADAPSO Software Industry Division published Dealing With Electronic Vandalism, in which they followed the risk of data loss by "the added risk of losing customer confidence"In response, free, open-source antivirus tools have been developed, and an industry of antivirus software has cropped up, selling or freely distributing virus protection to users of various operating systems
Computer_virus - Wikipedia, the free encyclopedia