What is what does the green dot mean on text messages?

The green dot on text messages refers to a status indicator in the Messages app on iPhones. It indicates that the person you are messaging is currently online or actively using their device. This feature is available in Apple's iMessage platform and indicates that the recipient is currently available to communicate. When the recipient goes offline or becomes inactive, the green dot will disappear, and you will be notified via a notification in the Messages app.