A frame buffer is a portion of random-access memory that contains a bitmap that drives a video display. It stores color values for every pixel to be shown. The frame buffer is a large, contiguous piece of memory with at minimum one bit per pixel, called a bit plane. A picture is built up in the frame buffer one bit at a time. Raster scan displays store picture definition in a memory area called the frame buffer, which holds intensity values for all screen points.

1. Raster and random scan
system/display

2. Frame Buffer
A frame buffer (frame buffer, or sometimes framestore) is a portion
of random-access memory (RAM) containing a bitmap that drives a video
display.
The information in the buffer typically consists of color values for
every pixel to be shown on the display.
A frame buffer is a large, contiguous piece of computer memory. At a
minimum there is one memory bit for each pixel in the rater; this amount
of memory is called a bit plane. The picture is built up in the frame buffer
one bit at a time.
Picture definition is stored in memory area called the Refresh Buffer or Frame
Buffer. This memory area holds the set of intensity values for all the
screen points.

3. Raster scan display

4. Raster scan

5. Raster Scan display

7. Random Scan display