A letter-quality printer operates in much the same fashion as a typewriter. An array of letters, numbers, or symbols embossed on a metal surface, are used to strike a ribbon of ink, depositing the ink on the page and thus printing a character.
Over time, several different technologies were developed including automating ordinary typebar typewriter mechanisms (such as the Friden Flexowriter), daisy wheel printers where the type is moulded around the edge of a wheel, and "golf ball" printers where the type is distributed over the face of a globe-shaped printhead (including automating IBM Selectric mechanisms such as the IBM 2741 terminal). The daisy wheel and Selectric-based printers offered the advantage that the typeface was readily changeable by the user to accommodate varying needs.
These printers were referred to as "letter-quality printers" during their heyday, and could produce text which was as clear and crisp as a typewriter (though they were nowhere near the quality of printing presses). Most were available either as complete computer terminals with keyboards, or as print-only devices. Because of its low cost, the daisy wheel printer became the most successful.
Letter-quality printers, however, were slow, noisy, incapable of printing graphics or images, generally limited to monochrome, and limited to a fixed set (usually one) of typefaces, though certain font effects like underlining and boldface could be achieved by overstriking. Nowadays, printers using non-impact printing (for example laser printers, inkjet printers, and other similar means) have replaced traditional letter-quality printers in most applications.