Block Chain API for BTC transactions
The result returned from that API is a compound JSON object containing:


Address basic information and summary
List of transactions associated with that address


The transactions are included in a JSON-encoded list under the txs key. Every transaction itself is a dictionary-like object holding pertinent information.

It should be pretty clear when you visualize it into a tree structure. You can use JSONView plugin for Firefox or Chrome - it'll render all application/json responses in a nice hierarchical and clickable tree and help you understand it.