D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG, and CSS. D3 emphasizes web standards and combines powerful visualization components with a data-driven approach to DOM manipulation, giving you the full capabilities of modern browsers without tying yourself to a proprietary framework.
Want to learn more? See the wiki.
For examples, see the gallery and mbostock’s bl.ocks.
The next major release of D3, 4.0, is coming! See the 4.0 development branch and read the new API reference to get ready.