If you're using an iPhone running iOS 5 or later, you'll notice that some of your text message bubbles appear blue instead of green. That's because when you message a fellow iPhone or iPad user, that text is actually sent via Apple's iMessage service. So what's the difference?
iMessages are actually send over your phone's data connection rather than your carrier's SMS service, meaning those iMessages don't count towards your text message limit (if you have one). In addition iMessage allows you to see when the other person is typing with an ellipses, provides a delivered receipt when your message has successfully gone through, and if it's turned on, will tell you when that person has actually Read that message. Pretty useful stuff.Read More