Anyone heard of Tapatalk?

I've heard of it, downloaded it to a phone but never understood what it is supposed to do or why I should use it.

Well, my mobile phone is Microsoft OS and I really don't plan on changing the OS unless forced to.As I said above, I have TapaTalk on the mobile phone but never found it useful. In addition TapaTalk seems to limit access to many functions of other boards. Lots of folk saying "I can't do that through TapaTalk". That leaves number three as my preferred option BUT I will tell you I almost never access websites using a phone except to check layout and function.