A file name is the unique identifier you give to a file for easy recognition, like "VacationPhoto" or "QuarterlyReport". The file extension, usually consisting of one to a few characters after the final period (like .jpg or .docx), tells the computer and its software what kind of data the file contains and which program should be used to open it. While the file name is chosen by the user and primarily for human reference, the extension acts as a technical label defined by the file format itself to instruct the operating system.

For example, a report written in Microsoft Word might be named "AnnualBudget.docx" – "AnnualBudget" is the file name, and ".docx" indicates it's a Word document. Similarly, a compressed archive file could be named "ProjectFiles.zip", where "ProjectFiles" is the name and ".zip" signifies it's a ZIP archive. These extensions dictate that the first file typically opens in Microsoft Word and the second file requires an unzipping tool like WinZip or built-in OS utilities.

File extensions are critical for the operating system to correctly associate files with applications, ensuring files open in the right program. Misnaming or removing an extension can cause a file to open incorrectly or not at all. While modern operating systems often hide extensions by default to simplify the user interface, understanding the distinction remains vital for managing files effectively and diagnosing opening errors.