The difference between HTML and HTM

Html=htm, only the former is the full name, the latter is abbreviated, there is no difference.

? ? So why are there two file formats?  ? ?

HTM is derived from the old 8.3 file format, the DOS operating system can only support the suffix length of 3, so is the HTM, but in Windows does not matter the HTM and html,html is a long file format named. So the HTM is to be compatible with the past DOS naming format exists, there is no difference in effect, the previous HTM and HTML as a different server hypertext file, has now been universal.

What is a 8.3 file format?

This is an old 16-bit Win95 or Win98 file system short file format, the extension is limited to 3 bits, the file name is limited to 8 bits, if you want to interact with a 15-bit system, you can not use a long file name, and must be converted

Only 8.3 file formats are supported in DOS in FAT disk format. If you want to do the application in this environment, you should pay attention to the format of this file, under NTFS, the default can be compatible with this file format, but also support the long file name, you can also adjust the registry to cancel the 8.3 file format support.