The 8.3 filename convention is a file naming system used in older operating systems, particularly MS-DOS and early versions of Windows. It allows filenames to be a maximum of eight characters long, followed by a period and a three-character file extension. This format helps identify the file type, such as ".txt" for text files or ".exe" for executable files. This convention was essential for maintaining compatibility with older software and hardware, which had limitations on filename lengths. While modern systems support longer filenames, the 8.3 convention is still relevant for compatibility with legacy systems and certain applications.