What is OpenGL:
OpenGL is a programming interface for rendering graphics. OpenGL 2.1 was released in 2006; most new games now require OpenGL 3 or higher. Making this change will help increase performance of the game, and supporting versions 2.1 and higher is a requirement for a part of the upcoming Minecraft plugin API. If your version of OpenGL is too old, and your Minecraft version is 1.6.4 or later, you'll see the following title "Old graphic card detected; This may prevent you from playing in the far future as OpenGL 2.1 will ve required."
How can I update to a newer version?
Some computers, such as older laptops and Apple computers, may not be able to upgrade to a newer version. Most desktop PCs can have their graphics cards swapped out for a newer card, with better performance. For information on upgrading your graphics card, contact your local PC hardware specialists.