Minecraft becoming an indie smash hit has spawned a new interest in using voxels for rendering games. In this talk I will show you how to render voxel worlds using WebGL. I will give you an introduction into all the data structures and algorithms needed to build an actual game using voxels. I will then show you some optimization that you can use to improve the performance of your voxel engine. I will not cover the basics of 3D rendering or game programming. I will not focus on a specific framework or library.