Television or TV is a telecommunication medium used for transmitting moving images in monochrome (black-and-white), or in color, and in two or three dimensions and sound. TV became available in crude experimental forms in the late 1920s. But it would still be several years before the new technology was marketed to consumers. After World War II, an improved form of black-and-white TV broadcasting became popular in the United States and Britain. And television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion. In the mid-1960s, color broadcasting was introduced in the US and most other developed countries. The availability of multiple types of storage media such as Betamax, VHS tape, local disks, DVDs, flash drives, high-definition Blu-ray Discs, and digital video recorders have enabled viewers to watch prerecorded material—such as movies— at home on their own time schedule.