Fun fact: it used to have 13 bars, but changed to the current 8 because 13 bars could not be made pretty on (8-pin) matrix printers.

Fun fact: exactly once, the team organising IBM's participation in the Copenhagen Pride parade got away with wearing t-shirts with the bars printed in the rainbow colours. Immediately after, they were notified that such alterations to corporate branding was unacceptable.
^(I cherish the two shirts I still have.)