Every one knows whatsapp and it uses all over world. It may download million of people and use it. It is available on play store iphone app. I used this app and I fell best experience with this social privet messenger. You can share with you privet video and photos to each other and you can create a group and enjoying group discuss by this app. And you can send any voice messege and share any videos link etc. So this is a best usefull app ever.