Files extensions are suffixes (like .txt or .jpg) added to filenames to help operating systems and applications identify the file type. You can save a file without an extension by simply omitting the period and the suffix during naming. While technically possible, operating systems like Windows often display a warning but allow it. Without an extension, the OS may not know which default application to use for opening it and will typically treat it as a generic, unknown file type.

For example, Unix/Linux configuration files (like /etc/hosts) frequently lack extensions by convention. Developers might also create temporary working files without extensions during programming. These are commonly handled manually or through specific scripts that recognize their purpose regardless of name formatting.

The main advantage is flexibility for specialized systems or conventions. However, the significant limitation is usability; users and most software rely heavily on extensions for seamless interaction. The lack of an extension can pose security risks, as malware might masquerade as harmless files. As a best practice, adding the correct extension enhances clarity and system interoperability, though extensionless files remain a valid, niche option when specific workflows require it.