The Closure tools help developers to build rich web applications with JavaScript that is both powerful and efficient. The Closure tools include: * A JavaScript optimizer: The Closure Compiler compiles JavaScript into compact, high-performance code. * A comprehensive JavaScript library The Closure Library is a broad, well-tested, modular, and cross-browser JavaScript library. * An easy templating system for both Java & JavaScript Closure Templates simplify the task of dynamically generating HTML - posavasos