Jimma it sounds like you're a mac user. Yes bin was used for OS 9 & earlier but would be very, very rare to see it used for OSX. Bin for windows is either a part of a cd image file or game, but for mac is similar to hqx & sit. If you know what you're looking for you should be able to guess which platform it belongs to. View other files in the search results of same size. Even browse someone with a bin file to see if their other files are for windows or mac. Not so many bin files for mac being shared nowadays.