It is hard to point to any one factor to explain the success of What’s My Line. More likely it was the fortuitous combination of all of them: celebrity judge panels, with A-list names mixed in with less known but no less important figures in business, politics, entertainment and countless other fields. Almost certainly, the element of mystery played into it: with the viewers at home playing along with the judges trying to figure out the profession of the mystery guest before them.

On this day, February 16, in 1950, What’s My Line began running on CBS. It lasted seventeen years and was adapted, before ending its run in the States, by Germany, Spain, UK, Brazil, as well as Brazil and Venezuela.

Fans of American Idol may find interesting the similar sponsorship terms of What’s My Line. Instead of Ford and Coca-Cola, it was a French deodorant “Stopette” first featured on the table of the judges, as well as on their scorecards and other places around the set. It may have been the first product placement deal in television history.