OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Instanced Rendering

Instancing, or instanced rendering, is a way of executing the same drawing commands many times in a row, with each producing a slightly different result. This can be a very efficient method of rendering a large amount of geometry with very few API calls. Several variants of already-familiar drawing functions exist to instruct OpenGL to execute the command multiple times. Further, various mechanisms are available in OpenGL to allow the shader to use the instance of the draw as an input, and to be given new values for vertex attributes per-instance rather than per-vertex. The simplest instanced rendering call is:

void glDrawArraysInstanced(GLenum mode, GLint first,                         GLsizei count, GLsizei primCount