A file extension is a suffix added to the end of a computer file's name, usually following a period (dot), that indicates the file's type or format and often suggests what kind of data the file contains or how it should be used. For example, in the filename "document.txt," the ".txt" is the file extension indicating a plain text file
. File extensions typically consist of two to four alphanumeric characters, though they can sometimes be longer, and they help the operating system determine which software application should open the file. For instance, ".docx" is associated with Microsoft Word documents, ".jpg" with image files, and ".exe" with executable programs
. The extension acts as metadata about the file, guiding both the computer and the user on how to handle the file. Different extensions correspond to different file formats such as text files, images, audio, video, compressed archives, and executable files. Some extensions may be shared by multiple file types or programs, which can sometimes cause confusion
. In summary, a file extension is a key part of a file's name that signals its format and the appropriate program to open it, ensuring proper handling and use of the file on a computer system
