R is a computer program that lets you analyze data. By “analyze” we mean, first, read the data into the program and then operate on it – drawing graphs and charts, manipulating values, fitting statistical models, and so on. R is both a statistical “environment” and also a programming language, and it is very widely used both in commercial and academic settings. R is free and open-source and runs on Windows, Apple, and Linux operating systems. It is maintained by a group of volunteers who release bug fixes and new features regularly.