Platforms
:)
The OpenGl code is the same on each platform but the setup and handling of the windows depends on the platform. Below is a overview on how it is done on each platform but first some multi-platform library's to make it possible to avoid writing any such code at all.
Multi-platform
GLFW - http://www.glfw.org
SDL - https://www.libsdl.org
SFML - http://www.sfml-dev.org
OpenGL Utility Toolkit (GLUT) - https://www.opengl.org/resources/libraries/glut
Common toolkit used in older samples and not active any more. No reason to use it in anything new. Look at GLFW instead.
Platform Details
Windows
To create the OpenGl context in a window one use the WGL API.
OSX
CGL and NSOpenGL.
Linux
On linux the interface to setup OpenGL is called GLX.
Reference