Blu-ray is a type of DISC that is used to store high-definition video and audio content. It was developed by Sony and Panasonic in 2002 and is now the most popular format for storing HD content. Blu-ray discs are capable of storing up to 25GB of data, which is five times more than a standard DVD. They also have a much higher resolution than DVDs, making them ideal for watching movies and other high-definition content.