What is a node in OPC-UA?

I have been reading around the internet for a good explanation of what a node is in OPC-UA. It seems there are libraries out there for it, but none actually explain nodes. What is the purpose of nodes in OPC-UA?

Note: OPC and OPC-UA noob here

I think you are talking about 2 different stuff here.

• the node concept of OPC UA: An OPC UA node is like an entity representing information. Some Nodes are Variables, DataType, References, Object, Methods... depending of what they are used for.

By reading the OPC UA Specification you will get a good overview here - Specially Part 1: Overview and Concepts and Part 3: Address Space Model (you need to create a free account first)

• NodeOPCUA, which is a Node.js implementation of OPC UA.