These are most of the important English language apps for Apple's iOS operating system, which supports the iPhone, iPad and iPod Touch. Sensei's Library  contains more details about these and other apps for the iPad and the iPhone . All items without prices are free.
If you're a beginner please have a look at our Tips for Beginners page  which contains our initial recommendations for you. In addition Go for kids  Capture Go! is very good as an introduction to Go, but not a complete game.
These all allow users to interact with other users, players and games on the servers they support. They all require you to get an account before you can use them.
Most of the following also allow for game recording and editing:
It's now difficult to categorise these programs since they seem to cover to different extents game playing (against a computer or a person), game recording and review, problem analysis