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A file type, often called a file format, is a standard way that information is encoded and organized for storage in a computer file. The file type tells the operating system and other applications how to interpret the data inside the file, such as whether it's an image, a document, or an executable program.

How file types are identified

File extension: The most common method for identifying a file type is the file extension—the suffix of letters that follows the period at the end of a filename (e.g., .docx, .jpg, .mp3). The operating system uses the extension to associate the file with the correct program needed to open or run it.

Internal metadata: Some file formats contain internal identifiers, such as a "magic number" at the beginning of the file, that provide a more definitive way for a program to confirm the file's format.