Software refers to a program or a set of instructions and applications used to manage and control various functions of a device such as a computer. Unlike hardware, which represents a physical part of a device, software is virtual.
There are two main categories of computer software: system software and application software. System software is a basic requirement for any computer, as it controls all main functions and integrates all parts into a unitary system. An example of a system software is an operating system.
Application software serves more specific purposes, such as creating databases and spreadsheets or processing images. Application software is available as single programs, software packages or software suites.