WebGL extends the capability of the HTML canvas element to allow it to render accelerated 3D graphics in any compatible web browser.
There are also many different webGL based 3D engines available:
- Three.js - the most popular and the most used
- Goo Engine
Getting started with webGL:
Start with WebGLFundamentals.org.
Other resources include LearningWebGL. LearningWebGL has basic tutorials.
If you don't want to learn WebGL and you just want to use a library that makes it easy to display 3d three.js is the most popular 3d library and there are plenty of Three.js tutorials and examples here - LearningThreeJS.