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The process of determining the set of pixels covered by a geometric primitive.
Think “frame” as in “single frame of a movie.” The framebuffer is the 2D array of pixels that stores a complete “frame” that the viewer will see on the next refresh cycle of the monitor. Continuously updated, somewhere around 60 times per second.

In a “dumb” framebuffer, the CPU has to update all the pixels. In modern programs, the job of updating of pixel values in the framebuffer is left entirely to the GPU. That frees up the CPU to do other things (AI, process game logic, etc).

Look really closely at your monitor. You’ll find that its really made up of thousands and thousands of tiny squares. Each of these tiny squares is called a “pixel”. “Pixel” stands for “picture element.” An average laptop monitor today has something like 1024×768 pixels on it.
A fragment is a “piece” of a pixel. Every final pixel that you see on your screen might be the result of blending together many different FRAGMENTS. That’s how you get cool looking images.

For instance, say you’re drawing a complex image from a computer game.

Imagine we’re looking through a water fall at some rocks.

We generate the pixels that should be shown on the monitor, we’ll actually TWO FRAGMENTS for each pixel. One fragment for the WATER at each pixel (which is partly see through), and other fragment for the color of the rock.

At a later stage, we will “blend” the fragments that resulted from drawing the water (which, like I said, are going to be partly see through) and the fragments from drawing the rock to form a single final PIXEL at each little square of the monitor. Every pixel in the end will just have regular RGB color values, even though FRAGMENTS can have some transclucency.


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