The document introduces competitive machine learning and provides an overview of what it is, why people compete, and where competitions can be found. Competitive machine learning involves using machine learning techniques to solve problems by analyzing messy and complex real-world data from sources like Netflix and Kaggle to build models that are evaluated on public leaderboards. Competitions help people gain experience and learn new techniques while allowing them to build portfolios and network, with some competitions offering prizes and job opportunities. Popular past competitions include the Netflix Prize and ImageNet challenges. The document recommends the Titanic competition on Kaggle as a good starting point for beginners.