Black-and-white laser printers are most common in work places. Laser printers produce very clean images. Since printers print images with a large number of small dots, the image quality is typically expressed in a measurement called "dpi" or "dots per inch." A 600 dpi printer is capable of producing 600 tiny dots per inch. For personal use, a large selection of inexpensive, yet very good, ink-jet printers are available. They are slower than laser printers, but image quality is very good. Color ink-jet printers are also gaining popularity. One can use a color ink-jet printer to make color transparencies as well.