One definition:
Z-Buffer
The z-buffer is a portion of the local memory that is used to store depth information about each pixel in a frame. Depending on what type of process is used, each pixel in the next new frame is checked against the values in the z-buffer - if the new pixel is nearer than the one in the z-buffer, its value overwrites the old one and appears in the final frame. However, if the new pixel is further away, then the old value remains in the z-buffer and the pixel is not displayed.
The z-buffer is often referred to as the depth buffer for obvious reasons.
Another z/w-article:
http://www.extremetech.com/article2/0,1697,1171859,00.asp
Z-Buffer
The z-buffer is a portion of the local memory that is used to store depth information about each pixel in a frame. Depending on what type of process is used, each pixel in the next new frame is checked against the values in the z-buffer - if the new pixel is nearer than the one in the z-buffer, its value overwrites the old one and appears in the final frame. However, if the new pixel is further away, then the old value remains in the z-buffer and the pixel is not displayed.
The z-buffer is often referred to as the depth buffer for obvious reasons.
Another z/w-article:
http://www.extremetech.com/article2/0,1697,1171859,00.asp