Files, Folders, and Drives
A file is a program or document. Everything on your computer is stored as a file.
Your computer usually comes with some program files that already have file names. When you create a new file, you give it a file name. Windows allows you to call files by many names up to 255 characters.
Each file has a three-letter file name extension that identifies the file type. For example, a document created using WordPad might have the file name letter to John.doc. The extension may sometimes identify the program that created the file.