[TypeScript](http://www.typescriptlang.org/) is a language for application-scale JavaScript. TypeScript adds optional types, classes, and modules to JavaScript. TypeScript supports tools for large-scale JavaScript applications for any browser, for any host, on any OS. TypeScript compiles to readable, standards-based JavaScript. Try it out at the [playground](http://www.typescriptlang.org/Playground), and stay up to date via [our blog](http://blogs.msdn.com/typescript) and [twitter account](https://twitter.com/typescriptlang).
1. Install [node](http://nodejs.org/) if you haven't already
2. Install dependencies ([Jake](https://github.com/mde/jake), [mocha](http://visionmedia.github.io/mocha/), [Chai](http://chaijs.com/) and [browserify](http://browserify.org/) the tool we use to build our compiler. To do this, run `npm install`.