Edward W. Bullard invented the hard hat in 1919, then patented it in 1929. It's credited with saving lives on job sites while also becoming a symbol of working-class America.

Work sites always have a lot going on, which is why it's important to stay organized. The different hard hat colors help show at a glance what job everyone has.

Getty Images. Or hard hats, evidently. Britain's Prince William stands with "DIY SOS" presenter Nick Knowles as he tours a house during his visit to Manchester. Phil Noble / Reuters. They wear ...