A computer virus is a type of malicious software program ("malware") that, when executed, replicates itself by modifying other computer programs and inserting its own code.
DOS is a family of disk operating systems.
The kilobyte is a multiple of the unit byte for digital information.
A virus is a small infectious agent that replicates only inside the living cells of other organisms.
.exe is a common filename extension denoting an executable file (the main execution point of a computer program) for DOS, OpenVMS, Microsoft Windows, Symbian or OS/2.