I think the reasons are : 1. It's free ( if you already have Internet on your phone ) 2. It's very easy to use and fast 3. The multimedia experience is bette

I think the reasons are : 1. It's free ( if you already have Internet on your phone ) 2. It's very easy to use and fast 3. The multimedia experience is better than MMS 4. Group chats 5. Network effects ( Some companies provide customer service through WhatsApp, your friends may already hang out in certain WhatsApp groups etc ) Unfortunately many people have to mute WhatsApp messages because they may be in a family group, getting too many messages and it may be considered rude to leave