If you're a photographer, you probably use an inkjet printer, most likely an expanded-gamut inkjet printer—one that uses six to eight inks, rather than the standard four (they're technically dyes, but most folks call them inks). The most common combination of expanded-gamut ink includes the four standard process colors—cyan, magenta, yellow and black (CMYK)—plus light cyan and light magenta. You may also have a choice of black inks, like glossy or photo black, matte black, light black, and even light light black (seriously!).
Inkjet printers are more common than dye-sublimation or color laser printers, so they're the focus of this section, but you can use printer and paper profiles no matter what kind of printer you use.
Nearly all expanded-gamut inkjet printers can convert your RGB images to CMYK (plus any additional inks they may have). For the best results (and the brightest colors), you should let the printer convert the color mode for you.
If you've already converted your RGB image to CMYK, don't panic—many of these printers can print a regular, four-color CMYK file, too. However, some print your image using CMYK inks and others convert your image into another color mode, like Lab (see Choosing Your Background) and then convert it to the printer's own so-called CMYK-Plus mode before printing it. The latter option can be scary because anytime you do massive color-mode shuffling like this, you can lose your brightest and most saturated colors. And ...