communications: A Shareware file compression utility written by Raymond Lau when he was in high school and used by virtually every Mac telecommunicator to reduce the size of files before spending time uploading them. The plain version is known as StuffIt Lite. Stuffit Deluxe is a more advanced version sold commercially. It has more features than StuffIt Lite, but both use the same compression format and algorithms. Names of files compressed by StuffIt should be tagged with a ".SIT" suffix, so others will know how to uncompress them. StuffIt can also decompress files compressed with PackIt, an older utility (those files end with the ".PIT" suffix).