Hurl is a command-line tool that allows users to run and test HTTP requests defined in a simple plain text format. It supports various features such as chaining requests, capturing values, and evaluating queries on headers and body responses. Hurl can be used for both fetching data and testing HTTP sessions, and it is adaptable for REST, JSON, HTML, and other types of APIs. The tool is lightweight, fast, and easy to integrate into CI/CD pipelines.