What is node?

Answer 1

A node class is simply a class representing a node in a data structure. Data structures like lists, trees, maps, etc. consist of so-called nodes. And a representation of such a node in form of a C++ class is called a node class.
https://www.codeproject.com/Questions/392196/What-is-a-node-class-in-cplusplus-and-how-to-imple

Answer 2

Node is a element list or binary tree.