This is a free app for iPad and is one I have picked out from quite a choice. The main screen shows a percussion kit of different drums and symbols that can be played just by tapping on them.

Like a drum kit from GarageBand, but taking up much less space on the phone or tablet, you can play as it is to make rhythms on your own or with someone else sharing the screen. As you get better, you can play along with some of the free sound loops, purchase more in-app or play along to something on the TV, radio, YouTube or wherever.