A dataset is a collection of data that has been organized and structured in a specific way to be used for analysis or research. It typically contains information on one or more variables, with each variable represented by a set of related values. Datasets can come from various sources such as surveys, government records, scientific experiments, or online databases, among others. They are often used in data science and machine learning to train models, test hypotheses, and make predictions based on patterns identified within the data.