Before iMessage, all text bubbles were green. For the original concept of iPhone, anything telephonic (that your carrier could charge you for, since Steve Jobs ensured that iPhones got unlimited data at first) was colored green. That’s why, to this day, the phone app and the messages app are both green, as well as the “you’re on a call” status that appears behind the clock.

Then iMessage came out in iOS 5 and they made it blue, the color of things that used data (like safari, stocks, mail, App Store, weather)

It wasn’t until the redesign of iOS 7 that they cranked up the saturation of all the colors, and the telephony green became like, anxiety-inducing electric green. I feel like that’s when people started hating these green bubbles so much, because iOS 7 actually made them an ugly, radioactive color. Where the blue remained a pleasant, calm ocean blue.