Possible differences between SDK's.

Question

I have seen many times from services selling hardware (e.g. small robots/drones/gadgets/etc) that they also provide their clients with an SDK to use along and create an application able to control/connect to the hardware.

I have read about SDK's a lot of things but still.. I have not exactly understood how does someone practically uses an SDK. What could the differences between the different SDK's be? These SDK's can normally be used only with a specific hardware? Is that SDK necessary to be used?

Answer 1

We use Android SDK to test the app in our cellphone,in Java we create the app and import It to android

Answer 2

but it depends of the language,the hardware.example:Arduino