This is part 2 of 3 about transferring data from a PHP page to an android app using JSON.
you can read part 1 here.
You may reach a point where you need to transfer data from a server (web-service) to a an android client. although, there are many ways to achieve that goal, one of the simplest is using JSON. JSON is better then XML in terms of small bandwidth footprint. it has a lot of libraries for every available platform, so it makes the best solution for server-client communication.