Espressif Systems ESP8266 Beginner's Manual page 12

HTTP and WebSocket both use TCP connections. What if you want lower latency? Well, Open Sound Control, or OSC, uses UDP to send
small pieces of data, like ints, floats, short text etc ... with very low latency. It was originally designed for controlling low latency audio
applications, but it's a very flexible protocol, so it's often used for low-latency tasks other than audio control.
Domain Name System
As mentioned before, you can only send a message to another computer if you know its IP address. But when you browse the Internet,
you only know a website's domain name (e.g. www.google.com). Your computer uses the Domain Name System to translate this
domain name to the right IP address. More on this later.
Sources
https://en.wikipedia.org/wiki/Internet_protocol_suite
https://en.wikipedia.org/wiki/Port_(computer_networking)
https://en.wikipedia.org/wiki/Transmission_Control_Protocol
https://en.wikipedia.org/wiki/Internet_Protocol
https://en.wikipedia.org/wiki/User_Datagram_Protocol