If you've been a user of Google's products, you'll probably know of all the chat services they had. They had so many it was so hard to keep track and it was a mess. Google have now sorted out this issue by releasing Google+ Hangouts.
Hangouts now unifies everything, putting everything under one umbrella. It allows you to have one-on-one or group conversations involving photos, emoji, videos and calls - all for free.
Hangouts is completely cross platform, it works on Android, iOS and the web. Messages stay in sync between all devices, so if you read a message on one device, it'll show as being read on another.
This is Google's attack on services like Apple's iMessage and WhatsApp. But Google beat iMessage by being multi-platform and it beats WhatsApp by being free so Hangouts is probably the best free messaging and calling service available right now. All you need is an internet connection.