High-Definition Television or HDTV is a digital television format delivering theater-quality pictures and CD-quality sound. HDTV offers an increase in picture quality by providing up to 1,920 active horizontal pixels by 1,080 active scanning lines, representing an image resolution of more than two million pixels. In addition to providing improved picture quality with more visible detail, hi-def offers a widescreen format and Dolby® Digital 5.1 surround sound. Cable program networks have been at the forefront of providing HD programming, and cable operators began delivering HD service in earnest to customers in 2002. Deployment has been on an upward arc ever since. The cable industry is also working closely with television set manufacturers to ensure that consumers receive HD in the most convenient and user-friendly ways possible.