A file extension is a suffix at the end of a computer file's name that indicates the file's type or format. It typically consists of a few letters (often three or four) following a period (dot) in the filename, such as .txt, .jpg, or .exe

. This extension helps the operating system and users identify what kind of data the file contains and which software program can open or execute it

. For example:

• .txt indicates a plain text file.
• .jpg indicates an image file in JPEG format.
• .exe indicates an executable program file on Windows systems

File extensions serve as metadata that guide the operating system in associating the file with the appropriate application to open or run it. Without the correct file extension, the OS might not know how to handle the file properly

. In summary, a file extension is a short code appended to a filename that defines the file's format and helps the computer know how to process or display the file.