How The Humble Index Card Foresaw The Internet

Index cards are mostly obsolete nowadays. We use them to create flash cards, write recipes, and occasionally fold them up into cool paper airplanes. But their original purpose was nothing less than organizing and classifying every known animal, plant, and mineral in the world.
Later, index cards formed the backbone of the library system, allowing us to index vast sums of information and inadvertently creating many of the underlying ideas that allowed the Internet to flourish.