Why are some iPhone messages green and others blue?
In iOS 7, the Messages app will display conversations with a green or blue background. If you’ve used iOS 6, you may have noticed that messages had a green or blue Send button. These colors are not random and actually tell you whether the message will be sent as a normal SMS text message or as an iMessage.
Green is for an SMS text message
The green background or Send button indicates that the message will be sent as a normal SMS text message using the messaging plan provided by your cell phone provider. Regular texting rates will apply, depending on your texting plan.
SMS text messaging is used automatically when sending a text message to someone who doesn’t have an Apple device. For example, if you are texting someone with a basic cell phone (not a smartphone) or any smartphone that is not an iPhone (Android, BlackBerry, Windows…), their iPhone will display the message on a green background (or have a green Send button for iOS 6 users). SMS text messaging has been around for years, even before the iPhone existed and everyone had basic cell phones.
Blue is for iMessage
The blue background or Send button indicates that the message will be sent as an iMessage.
Apple sends an iMessage instead of your cell phone provider. The iMessage is sent over an Internet connection rather than through the cell phone’s control channel. Your cell phone provider doesn’t charge text messaging fees when you send an iMessage.
When you send someone a message with an Apple device, your iPhone automatically recognizes if the sender has an Apple ID and sends the message as iMessage. On your iPhone, the message will display with a blue background (or have a blue Send button for iOS 6 users).
Apple routes iMessages based on a user’s Apple ID. So anyone with an iPad or Mac can send iMessages. However, because the iPad or Mac computer does not have access to a cell phone control channel, it cannot send regular SMS text messages.
Your iPhone automatically determines whether a message is sent as a normal SMS text message or as an iMessage. There is no need to worry about selecting one method or another. However, if you want some control over when an SMS or iMessage is sent, check out the messaging options in iPhone settings.