Axios is a promise-based HTTP client for the browser and Node.js. It allows developers to easily make HTTP requests to REST APIs, handle responses, and manage request configurations. Axios supports features like intercepting requests and responses, automatic transformation of JSON data, and client-side support for protecting against XSRF. Widely adopted, Axios simplifies communicating with backend services, making it a crucial tool for modern web development. Its ease of use and extensive features make it a popular choice for handling HTTP requests.