What does a "Framebuffer" do?

What does a "Framebuffer" do?

• It allows for smoother frame rates whilst in an active remote session by using a portion of RAM
• It stores an in-memory bitmap for conversion to a video signal that can be displayed
• It renders bitmap images in a dot matrix data format, displaying a rectangular grid of pixels
• It stores and displays a graphical image as a rectangular array of pixel colour values. 

EXPLANATION

A framebuffer (frame buffer, or sometimes framestore) is a portion of RAM containing a bitmap that drives a video display.
It is a memory buffer containing a complete frame of data. Modern video cards contain framebuffer circuitry in their cores.

SOURCE

https://en.wikipedia.org/wiki/Framebuffer