Graph nodes are fundamental components of a graph, which is a data structure used to represent relationships between objects. Each node, also known as a vertex, can hold data and is connected to other nodes through edges. This structure allows for the modeling of various systems, such as social networks, transportation routes, and computer networks. In a graph, nodes can represent anything from people in a social network to cities in a transportation map. The connections, or edges, between nodes indicate relationships or pathways, making graphs a powerful tool for analyzing complex systems and understanding how different elements interact with one another.