I searched on some forums for help, but so far i still don't understand. What is the diference between a node on a VPS and an user keeping his core wallet open 24/7. What i know is that when you transform your VPS into a full node, you're basically compiling the wallet and keep it open 24/7 on that VPS. But if i keep my core wallet open 24/7 on my PC is still a node? Also, what is the use of rcp_user and rcp_password ? Don't hate plz.
A node is what miners broadcasts their blocks to in order to add them to the blockchain. The more nodes that are up, the stronger the network. A node can be a handful of things, like a wallet running a full copy of the blockchain is a node (bitcoin core client), it can be something like a raspberry pi with software to run a fully copy of the blockchain or something like bitseeds full nodes they sell (
https://bitseed.org/).
Basically its anything that runs a full copy of the blockchain, and is connected to the internet to broadcast or rebroadcast transactions in order to keep the ledger up to date and accurate, and if you are a Bitcoin supporter, I cannot stress enough how important it is to run a full node if you can, as it helps support the community and network of Bitcoin.