On June 13, 1944, Grace Hopper and her team at Harvard University made an entry in their logbook that has become legend: a moth found trapped in the relay of the Mark II computer, causing it to malfunction.

Hopper taped the moth into the logbook with the notation: "First actual case of bug being found."

This is often cited as the origin of the term "computer bug." It was not — the term had been used for decades in engineering to describe mechanical defects. What the logbook entry represents is something more significant: the documentation culture Hopper insisted on.

Hopper believed that programs should be documented, readable, and reproducible. At a time when programming was regarded as trade craft — notes kept in shorthand if at all — she insisted on rigor, complete records, and transferable knowledge.

This insistence shaped every software development practice that came after. Version control, documentation standards, the idea that code should be readable by someone other than its author — these all trace to habits Hopper established when debugging relay computers in the 1940s.

The moth is in the Smithsonian. Hopper's documentation philosophy is in every codebase in the world.