What is the function of the fuser in a laser printer?

A copier or laser printer uses dry ink called toner, a fine plastic powder, to create an image. The toner is selectively placed on a light-sensitive surface which has been exposed to the image to be copied. It is then transfered to paper. At this point it is just loose dust on the surface of the paper and could be easilly brushed off.

The paper with the toner on it passes between heated rollers which press the toner into the paper and melt it at the same time. The result is an image permanently fixed to the paper.

The heated roller is the Fuser, because it fuses the toner to the paper.