Most iPhone users are familiar with the green message bubbles that appear when texting Android phones, but occasionally these pop up when messaging other iPhones, too. When a message can’t be sent via iMessage, it will fall back to a text messaging standard, and this results in green bubbles appearing even on the best iPhones. Aside from being an annoyance, green bubbles can lack iMessage-exclusive features. So, if you’re seeing green bubbles and want to know why, we’ve got the answer.