Resources

Browser support

Also list feature support, usage and how to detect support

get.WebGL.org

CanIuse.com/#search=WebGL

BrowserLeaks.com/WebGL

WebGLreport.com

WebGLstats.com

Learning and reference

WebGL Fundamentals
WebGL from the ground up. No magic.

WebGL 2 Fundamentals
WebGL2 from the ground up. No magic.

Learning WebGL
Learning WebGL

Learning Three.js
Learning Three.js

Online courses (video)

Interactive 3D Graphics: Creating Virtual Worlds
Udacity.com/course/cs291

Interactive Computer Graphics with WebGL (Angel)
Coursera.org/Course/WebGL

Introduction to WebGL 3D with HTML5 and Babylon.js
MicrosoftVirtualAcademy.com/Training-Courses/Introduction-To-WebGL-3D-with-HTML5-and-Babylon-js

Computer Graphics (UC San Diego)
edx.org/course/computer-graphics-uc-san-diegox-cse167x

Foundations of Computer Graphics (BerkeleyX) 
courses.edx.org/courses/BerkeleyX/CS184.1x/2012_Fall/