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.

Since President Woodrow Wilson declared June 14 Flag Day in May 1916, the United States has honored the adoption of the stars and stripes in a number of ways, including carrying the flag in parades, displaying it outside homes and holding other patriotic events. Before 1916, a number of states and cities had started to observe the day.

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.