SIT, StuffIt Archive (.sit)
The SIT Archive file format
SIT files are created by the Smith Micro StuffIt software. StuffIt is commonly used on Apple Mac computers to compress (or "stuff") different types of files. Nowadays, SIT files are not Mac-exclusive anymore and can be opened on computers running with the Windows operating system as well.
Technical details of SIT files
SIT was the first file extension used for files compressed using StuffIt. Newer versions of StuffIt use the SITX extension.