Joliet is the name of an extension to the ISO 9660 file system. It has been most heavily endorsed by Microsoft and has been supported by all versions of its Windows OS since Windows 95 and Windows NT. Its primary focus is the relaxation of the filename restrictions inherent with full ISO 9660 compliance.
Joliet accomplishes this by supplying an additional set of filenames (up to 64 Unicode characters in length) to be encoded in UCS-2. These filenames are stored in a special supplementary header that is safely ignored on non-Joliet systems, thus preserving backward compatibility.
Official operating system support is provided only with Microsoft Windows, Linux and FreeBSD. Most disc-creation software creates both Joliet and Rock Ridge extensions on the disc, thus allowing files appear to have the same characteristics where one or the other extension is not supported.