This document introduces graph neural networks and discusses a claim that they are essentially low-pass filters. It provides an overview of graph neural network operations, including combining node features, aggregating information from neighbors, and updating node representations over multiple layers. The document notes that while graph neural networks may be less powerful than other deep learning methods, they are interesting for problems involving graphs, such as drug discovery and web analytics. It questions how graph neural network classifications operate and whether the low-pass filter behavior is caused by the graph Laplacian matrix.