ES6, or ECMAScript 2015, is a major update to the JavaScript programming language that introduced new features to enhance code readability and efficiency. Key additions include arrow functions, classes, and template literals, which simplify syntax and improve the way developers write and manage code. Another significant aspect of ES6 is its support for modules, allowing developers to organize code into reusable components. This modular approach helps in maintaining large codebases and promotes better collaboration among developers. Overall, ES6 has played a crucial role in modernizing JavaScript and making it more powerful for web development.