What's the difference between text messaging and iMessages? Text messaging requires that you have a cellular plan while iMessages allow you to send messages using your cellular data or Wi-Fi. This is especially handy if you're travelling internationally with only a Wi-Fi connection, or if you want to send messages from an Apple device without cellular connectivity. If the message you send is blue, it's an iMessage; if green, it's a text message. Here's how to set iMessages up if you haven't already.
Open Settings. Scroll down to Messages.
If iMessage is off, slide the circle right. If you aren't already logged into iCloud with your Apple ID, a blue message will appear: Use your Apple ID for iMessage. If you are not logged in, tap the message to do so.
With iMessage you can send texts from your phone number, email address, or Apple ID. To change which, tap Send & Receive within the Messages menu. Here, you can add another email to be reached by via iMessage and control which (number or email) is used when starting conversations. 
Want to let people know when you've seen the message they sent you? Return to the Messages menu, tap Send Read Receipts and slide the circle right.
If you are experiencing issues with your iMessage not working on Mac or other devices, check out these troubleshooting tips!
