SIT - StuffIt Archive
This is a file type similar to .ZIP compressed files for Windows systems, a .SIT file is the common file compression format supported by the Apple Macintosh. Smith Micro StuffIt software was originally designed as a Mac only compression scheme. Today, however .SIT files are now cross-platform and may be created and opened by either Mac or Windows operating systems. .SIT files were initially developed by Allume Systems (was originally called Aladdin Systems), it is now distributed and developed by Smith Micro.