The man who made music portable and accessible for millions has died at the age of 94.
Lou Ottens died in his hometown of Duizel, in the Netherlands.
Ottens became the head engineer at Royal Philips in 1960 when he and his team began working on ways to make recordings more portable. Up until that time, the only real options were reel-to-reel tapes and vinyl records. In 1963 the team unveiled the compact cassette.
The BBC says that it's been estimated that over 100 billion cassette tapes have been sold worldwide since their 1963 debut.
Ottens was also part of the team that introduced the CD in 1982. According to the BBC, when he first introduced the CD player he said ""From now on, the conventional record player is obsolete."
The cassette tape has been making a comeback in recent years, thanks to artists releasing new projects on the classic format.