This document provides an overview of artificial neural networks (ANNs). It begins by defining ANNs as models inspired by biological neural networks in the brain that are used to estimate functions. It then describes how biological neural networks operate in the brain with interconnected neurons. The document outlines several key properties of ANNs including plasticity, learning from experience, and their use in machine learning applications to improve performance over time. It proceeds to discuss early ANN models like the perceptron and limitations, before introducing multi-layered networks and backpropagation training. Finally, it briefly introduces self-organizing maps that can learn without supervision.