PKZIP (also capitalized as PKZip) is a program, originally written for the DOS operating system , that gathers multiple files into a single compressed file that can be stored in less space and transmitted more quickly from one place to another. A companion program, PKUNZIP, uncompresses and restores the original files when they are needed. The compressed file archive is known as a zip file and conventionally has a .zip file name suffix. The "PK" derives from the name of the program's inventor, Phillip W. Katz. Katz is said to have developed the idea in 1986, working at his mother's kitchen table. PKZIP became one of the most popular shareware programs ever written and, with various platform distributions, an industry standard.
The original owner, PKWARE, still distributes the program in versions for a number of different operating system platform s. Several other companies also distribute cross-platform versions that enable files to be economically exchanged between locations. For example, a company with an IBM OS/390 ( MVS ) platform can use PKZIP MVS to build an archive that can be transmitted to a Sun Solaris ( UNIX ) platform or to an IBM OS/400 platform where it can be unzipped using PKUNZIP UNIX.
Windows users often use WinZip , another popular program that also uses the .zip file format.