Software is a program that enables a computer to perform a specific task, as opposed to the physical components of the system (hardware). This includes application software such as a word processor, which enables a user to perform a task, and system software such as an operating system, which enables other software to run properly, by interfacing with hardware and with other software. Software also acts as an interface between the hardware like processor(s) and user(s).
Photoshop is available for Windows, OS X, and Mac OS; versions up to Photoshop 9.0 can also be used with other operating systems such as Linux using software such as CrossOver. Past versions of the program were ported to the IRIX and Solaris, but official support for this port was dropped after version 3.
The current (12th) version of the program, Photoshop CS5, was released on April 12, 2010. "CS" reflects its integration with other Creative Suite products, and the number "5" represents it as the fifth version released since Adobe re-branded its products under the CS umbrella in 2003. Photoshop CS5 features additions such as three dimensional brushes and warping tools.