The field of Machine Learning (ML)Machine learning develops algorithms to make machines learn from experience without being explicitly programmed. A great many proposals for ML systems were made in the twentieth and twenty-first centuries, but one important class of system is the artificial neural network (ANN)Neural networkartificial. Today, ANNs are deployed in operational settings by governments and businesses around the world for a wide variety of tasks from language translation to face recognition. In this chapter, we introduce the concept of artificial neural networks and how to use them. ANNs are loosely modeled on the human brain. The human brain consists of a densely connected set of nerve cells called neurons. Signals pass between neurons via complex electro-chemical reactions. ANNs seek to replicate this system with a set of artificial neurons connected to one another to form a network (giving rise to the name artificial neural network). Figure 2.1 shows an example of an ANN.