Ive been trying to implement the WebSocket protocol from scratch in nodejs, doing so i have a question thats since been unawnsered. What exactly are subprotocols in regards to websockets? The second parameter of the WebSocket constructor is where you specify "subprotocols" -

```
let socket = new WebSocket("ws://localhost:3000",["http",...]);

```

Can anybody give me a clear awnser to what purpose they have?