U+1F44D
The thumbs up emoji is the internet's quick nod of approval. People send it to mean yes, agreed, sounds good, or message received, usually when typing a full reply would feel like overkill.
It reads as warm and positive in most chats. A few people half-joke that a lone ð can come off as a bit blunt, so it's worth reading the room, but in everyday messages it's about as friendly as a reply gets. It also comes in five skin tones, so you can pick the one that feels like you.