RFB or "Remote Frame Buffer" protocol was created in the Olivetti Research Laboratory to manage graphic interfaces remotely. The idea was to create a protocol as simple as possible, so as much hardware as possible (thin clients) could deal with it. One of its simplest function is to draw rectangles specifying basically 5 parameters: x position, y position, width, height and color. In that way an image can be composed of multiple rectangles, sending only 5 parameters per rectangle and there's no need to send desktop image pixel by pixel to the thin client, saving bandwidth.
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