This is to make it possible to create a multi-line comment without temporarily commenting out all the code from the /* to the end of the file or to the end of  the next already existing multi-line comment.  This makes it possible to keep your file in a syntacticly correct state.  This allows you to use things like tag navigation or statement navigation to move to the location where you want to end the comment.  When you type */ in order to close the comment, the editor will search backwards for a matching /**/ and patch things up by deleting the */ characters.  The unique thing about this technique is that it gives you the benefit of keeping your code syntactically correct without actually changing what you type to create a comment at all.  You still type /*, then move your cursor down, then type */, just like you did before.