Clojure is a modern, dynamic, and functional programming language developed by Rich Hickey. It's designed to compile down to bytecode and run on a virtual machine, making it OS-independent and compatible with the JVM, JavaScript, or Microsoft CLR. Clojure has a strong focus on concurrency and parallelism, with features like channels, threads, and futures. The language is also known for its macro system, which allows developers to extend the language itself. Leiningen is a popular build tool that integrates well with Clojure, making it easy to manage projects and dependencies. With Leiningen, users can create a new project, install dependencies, compile code, run tests, and even generate an uberjar for distribution. The language has a strong community and a wide range of resources available, including the official documentation, tutorials, and libraries like Twilio's API library. Clojure is often compared to other functional programming languages like Lisp, Scheme, and Haskell, but its syntax is designed to be more concise and expressive. Overall, Clojure is a powerful and flexible language that's well-suited for building scalable and maintainable software systems.