WebGL handles geometry in a standard way, independently of the complexity and number of points that surfaces can have. There are two data types that are fundamental to represent the geometry of any 3D object: vertices and indices.
Vertices are the points that define the corners of 3D objects. Each vertex is represented by three floating-point numbers that correspond to the x, y, and z coordinates of the vertex. Unlike its cousin, OpenGL, WebGL does not provide API methods to pass independent vertices to the rendering pipeline, therefore we need to write all of our vertices in a JavaScript array and then construct a WebGL vertex buffer with it.
Indices are numeric labels for the vertices in a given 3D scene. Indices allow us to tell WebGL how to connect vertices in order to produce a surface. Just like with vertices, indices are stored in a JavaScript array and then they are passed along to WebGL's rendering pipeline using a WebGL index buffer.