Sony Corporation (commonly known as Sony and stylized as SONY) is a Japanese multinational conglomerate corporation headquartered in Kōnan, Minato, Tokyo.

Its diversified business includes consumer and professional electronics, semiconductors, gaming, entertainment and financial services. Sony introduced U-matic, the world's first videocassette format, in 1971, but the standard was unpopular for domestic use due to the high price.

U-matic is an analogue recording videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. 

It was among the first video formats to contain the videotape inside a cassette, as opposed to the various reel-to-reel or open-reel formats of the time. 

The videotape is 3⁄4 in (19 mm) wide, so the format is often known as "three-quarter-inch" or simply "three-quarter", compared to open reel videotape formats in use, such as 1 in (25 mm) type C videotape and 2 in (51 mm) quadruplex videotape.

Sony used the Compact Cassette format in many of its tape recorders and players, including the Walkman, the world's first portable music player. Walkman (stylized WALKMAN) is a brand of portable media players manufactured by Sony.

The original Walkman, released in 1979, was a portable cassette player that allowed people to listen to music of their choice on the move. Its popularity made "walkman" an unofficial term for personal stereos of any producer or brand. By 2010, when production stopped, Sony had built about 200 million cassette-based Walkmans.

According to en.wikipedia