It’s Flag Day, a day that honors the adoption of the United States flag on June 14, 1777. The original resolution declared the flag would have 13 alternating red and white stripes and a blue field with 13 white stars, representing a new constellation — a powerful symbol of unity and independence that continues to fly proudly today.

This Father's Day weekend brings another, more obscure holiday in the U.S.: Flag Day. Here's what the holiday is and how and when it started.