Over time, an inkjet printer is about ten times more expensive to operate than a laser printer because ink needs replenishing more frequently. A laser printer uses a non-impact (keys don't strike the paper) photocopier technology. When a document is sent to the printer, a laser beam "draws" the document on a selenium-coated drum using electrical charges. After the drum is charged, it is rolled in toner. The toner adheres to the charged image on the drum and is transferred onto a piece of paper and fused to the paper with heat and pressure. After the document is printed, the electrical charge is removed from the drum and the excess toner is collected.