Knockout.js is a powerful JavaScript library that makes it easy to create rich, interactive web applications. It allows developers to quickly create complex user interfaces with simple and clean coding. With Knockout.js, developers can define Model-View-ViewModel (MVVM) patterns, which are used to separate the presentation layer from the business logic layer. This separation provides a great way to keep your code organized and maintainable. Knockout.js also offers powerful features such as declarative bindings, dependency tracking, and templating. These features allow developers to create powerful and dynamic web applications without writing a lot of code. Knockout.js is an invaluable tool for web developers looking to create feature-rich and dynamic web applications.