In this chapter, we have covered what machine learning is and why it is so important. We have provided several examples where machine learning techniques find applications and what kind of problems can be solved using machine learning. We have also introduced a particular type of machine learning algorithm, called neural networks, which is at the basis of deep learning, and have provided a coding example in which, using a popular machine learning library, we have solved a particular classification problem. In the next chapter, we will cover neural networks in better detail and will provide their theoretical justifications based on biological considerations drawn from observations of how our own brain works.