This chapter provides an overview of four common types of probability: classical probability; frequentist probability; subjective probability; and conditional probability. It offers adults and students an opportunity to learn about probability and then apply what they’ve learned to make predictions. The chapter includes a set of questions for reflection and a list of suggested resources. Scientific studies such as drug trials are designed based on frequentist probability. Many people trust subjective probability over more scientific approaches to making predictions. Probability is an idea that enables us to make reason-based decisions about many aspects of our lives. From predicting heads-or-tails when flipping a coin or using poll results to determine a proposed law’s likelihood to be passed to looking at a weather forecast to see what clothing to lay out for the morning, we are relying on the probability that something will or will not happen. But predictions are not infallible.