For anyone who is not familiar with the terms it is basically shorthand for having the multitrack files. Basically having a separate file for each instrument plus a click track. As long as you are working with a DAW (pro tools, logic, cubase , ets...) you can mix it how you want and take out any parts that may be playing live.  I have several tracks already posted as stems. I just want people to know that every track I have is available as stems. If it is not posted just email me and ask for it. Typically it can be done the same day