It lists every useful piece of software on your computer, including commands, programs, and files. That’s why the Start menu is so important ( Figure 1-4). They may as well bear a sticker reading, “No user-serviceable parts inside.” The vast majority of them are not for you they’re support files, there for behind-the-scenes use by Windows and your applications. Windows is composed of 50 million lines of computer code, scattered across your hard drive in thousands of files.