A Graph Neural Network (GNN) is a neural architecture that operates on graph-structured data, where entities are represented as nodes and their relationships as edges. Its core mechanism is message passing, where nodes iteratively aggregate information from their neighbors to build rich, contextual representations. This allows GNNs to learn patterns from the topology and features of the graph, making them fundamental for tasks like node classification, link prediction, and graph classification in domains like social networks, molecular chemistry, and knowledge graphs.
