WhatsApp for Android: The ultimate guide
Android Central - 12-06
WhatsApp has 1.5 billion users, and it's not hard to see why. You can send text messages, photos, videos, contacts, and locations, make calls, receive calls, and manage messages like a boss, for free. Yeah, free. No per-minute rate for calling internationally, or premium per text message sent or text message received. It's all free. All you need is an internet connection and an existing phone number and away you go!