Philips CD-i console, also known as Green Book, which was co-developed by Philips and Sony. In addition to games, educational and multimedia reference titles were produced, such as interactive encyclopedias and museum tours, which were popular before public Internet access was widespread. The CD-i was also one of the earliest game systems to implement Internet features, including subscriptions, web browsing, downloading, e-mail, and online play. This was facilitated by the use of an additional hardware modem and "CD-Online" disc (renamed Web-i in the US), which Philips initially released in Britain in 1995 for $150 US. Development of the CD-i format began in
Green Book (CD standard) on CD-i tracks, as well as certain specific files that are required to be present in a CD-i compatible disc. The CD-i Ready format is a type of bridge format, also designed by Philips, that defines discs compatible with CD Digital audio players and CD-i players. This format puts CD-i software and data into the pregap of Track 1. The CD-i Bridge format, defined in Philips' White Book, is a transitional format allowing bridge discs to be played both on CD-ROM drives and on CD-i players. Green Book (CD standard) The "Green Book", formally known as the "CD-i Full Functional