A computer program is a set of instructions written in a programming language that a computer can execute to perform a specific task. These instructions can be in the form of source code, which is human-readable, or machine code, which is the binary representation of the source code that the computer can execute directly. A program can be characterized as interactive or batch in terms of what drives them and how continuously they run. Programs can be categorized along functional lines, with the main functional categories being application software and system software. Examples of computer programs include Microsoft Word, Adobe Photoshop, and web browsers like Chrome and Firefox. Without programs, a computer would only be able to operate with the operating system but would be incapable of doing anything else.