tl;dr: Digg was the original reddit - much bigger, reddit was the underdog. Digg did a redesign that was absolutely horrible and created a huge backlash. Becau

tl;dr: Digg was the original reddit - much bigger, reddit was the underdog. Digg did a redesign that was absolutely horrible and created a huge backlash. Because Digg did not create a backup/proper versioning, they couldn't go back to the old design, and people migrated to reddit. The rest, as they say, is history.