For more detailed info goto http://polymer-project.org/.
Polymer is a new type of library for the web, designed to leverage the existing browser infrastructure to provide the encapsulation and extendability currently only available in JS libraries.
Polymer is based on a set of future technologies, including Shadow DOM, Custom Elements and Model Driven Views. Currently these technologies are implemented as polyfills or shims, but as browsers adopt these features natively, the platform code that drives Polymer evacipates, leaving only the value-adds.
Tools & Testing
For running tests or building minified files, consult the tooling information.
Release (tagged) versions of Polymer include concatenated and minified sources for your convenience.