Text Relay Service is a communication service that helps individuals who are deaf, hard of hearing, or have speech difficulties to communicate over the phone. It connects a person using text with a relay operator who reads their message aloud to the other party and types the spoken response back to the text user. This service allows for seamless conversations between people who use text-based communication and those who use traditional voice calls. It ensures that everyone can participate in phone conversations, promoting inclusivity and accessibility in communication.