Nodes in graph structures are fundamental components that represent entities or objects within a network. Each node, also known as a vertex, can hold various attributes that provide additional information about the entity it represents. In a graph, nodes are interconnected by edges, which signify relationships or connections between them. Graph structures can be directed or undirected, weighted or unweighted, and are widely used in various applications, including social networks, transportation systems, and biological interactions. Understanding nodes and their relationships is crucial for analyzing complex systems and solving problems in fields such as computer science, data science, and artificial intelligence.