All materials associated with computer operations other than the actual machinery (the hardware). Essentially, software is a set of instructions for a computer, installed via a variety of media, including CD-ROMs, discs or the Internet, or created and installed manually in the computer, using the keyboard. Most software is grouped into two categories of programs— system software and application software. System software controls basic programs that permit the computer to operate, while application software instructs the computer to perform specific, practical tasks such as word processing or accessing the Internet. Computer owners can purchase or copy an almost limitless variety of software, although the amount that any given computer can store is limited by computer capacity, and it can be more convenient to access software programs over the Internet just long enough to perform a specific operation without installing the software onto the user computer.