As used by a computer, a collection of related data or program records stored as a unit with a single name. Almost all information stored in a computer must be in a file. There are many different types of files: data files, text files, program files, directory files, and so on. Different types of files store different types of information. For example, program files store programs, or “executable” code, whereas text files store text, or code that’s in the form of common ASCII characters recognizable as text. Files are always in a particular format. For example, if you created a Microsoft Word document, the file is saved so that Microsoft Word can read it and open it. Often files cannot be opened to read using conventional programs, they are simply data files the computer understands. Files are usually represented by the filename and an extension, which often specifies what type of file it is.