What is Polymer?
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.
Why Web Components?
We’re best known for our work on Web Components, a set of modern web standards that give you the power to extend HTML.
With Web Components, you can create and share custom elements that work on any site, interoperate seamlessly with the browser’s built-in elements, and play nicely with frameworks of all kinds.
If you like, you can build your app entirely out of Web Components. Breaking your app up into right-sized components helps make your code cleaner and LESS expensive to maintain.
Products like LitElement and PWA Starter Kit make Web Components easier to use and highlight best practices, helping you get great results.