If you're an iPhone user, you might have noticed that sometimes your 'sent' messages in the iMessenger app are different colours. Sometimes your messages are highlighted in blue text bubbles, while other times, those bubbles are green... why is that exactly?
Apple iMessage is an application where you can send and receive text messages, audio, images and GIFs. But, what makes iMessage unique, in comparison to other apps such as WhatsApp and Telegram, is the fact that it supports SMS text messages as well.
If you are sending and receiving messages to another iPhone user over data, all your messages will appear in a blue text bubble. But, if you send or receive an SMS, the bubble will appear green in colour to differentiate an SMS from an internet message.
Also, iMessage is only available for iPhone users, so if you were to text an Android user, all the messages will also appear green. You might also experience green messages to an iPhone user from time to time in the event that the user you're texting is out of network range, out of data, or if their phone is off.
Take a look at the video below by the YouTube channel, Apple Explained, on Why iPhone Messages Turn Green.