Single Wire Protocol (SWP) is like having a secret code that only one person knows, and they use it to talk to other people without anyone else understanding what they're saying.
In technology, SWP is used to connect things like SIM cards (the little chip in your phone that lets you connect to the internet and make calls) to other devices, like the motherboard in your phone. It uses just one wire (which is like a long piece of string that connects different parts) to send and receive data, instead of a bunch of wires like you might see in other things.
SWP is really good because it doesn't take up much space or use a lot of power, which is important when you're making something small like a phone. And because only the right people (like your SIM card and your phone's motherboard) know the secret code, it helps to keep things safe and secure.
So SWP is like a secret code that helps important parts of your phone or other devices talk to each other really well, without anyone else knowing what they're saying.