In 1985, Microsoft asked Encyclopaedia Britannica to partner on a CD-ROM edition. Britannica said no. Its business rested on door-to-door salesmen persuading parents to spend $1,000 to $1,500 on leather-bound prestige, and a cheap plastic disc looked like a toy that would eat its own profits. So Microsoft licensed the text of Funk and Wagnalls, the encyclopedia sold volume by volume at the grocery store, and built a multimedia shell around it under the code name Gandalf.

Encarta launched in 1993 at $395, soon dropped to $99, and then came bundled with new home PCs. This episode covers how it squeezed an interactive world onto a 680 megabyte disc, why its regional editions set off a public argument about whether facts should change by country, and how a closed, professionally edited product lost to a free site anyone could edit. Microsoft discontinued Encarta in 2009, undone by the same kind of shift it had once forced on print.

• Premium editions held over 62,000 articles, 25,000 pictures, and more than 300 videos and animations, made to fit with MIDI audio, vector graphics, and postage-stamp video clips.
• Extras included the MindMaze castle trivia game, 3D virtual tours of sites like the Acropolis, and dynamic maps drawn by the engine behind Microsoft MapPoint.
• Microsoft absorbed the content of rivals such as Collier’s, ending their lives in print.
• Former Britannica editor-in-chief Robert McHenry accused Encarta of pandering to local prejudices in its national editions, and Bill Gates answered with an article of his own.
• Encarta moved to a web subscription model around 2000 and let users suggest edits by 2005, but Wikipedia updated by the minute while Encarta still waited on editorial review.