Info needed on JSON messages

Hello.  I hope someone can help me.  I've been reading the API documentation and note that both JSON and Protobufs can be used to interact with the API.

Protobufs are a new concept to me so my default position is to use JSON.

I've seen lots of information on Protobufs but little on JSON.  Can anyone point me to a resource that describes the JSON requirements in the same detail as Protobufs?

I'm a newbie to the API so if anyone knows of a good example of Python code that gives me the basics of connecting to an account and sending/retrieving information, that would be marvellous.

Thanks.

Philip