Flag Day is celebrated annually in the U.S. on June 14. Here are some key things to know about the holiday.

How did Flag Day originate?

Flag Day has a long history and began on the local level. Its origins date back to 1885, when a schoolteacher in Wisconsin had his class honor "Flag Birthday" on June 14 to mark the anniversary of the Flag Resolution of 1777. From there, communities across the country began to mark the day, according to americaslibrary.gov. On that day, June 14, 1777, John Adams spoke about the flag at a meeting of the Continental Congress in Philadelphia.

Jul 26, 2016; Springfield, NJ, USA; A general view of an American flag waving outside the clubhouse during a practice round for the 2016 PGA Championship golf tournament at Baltusrol GC - Lower Course. Mandatory Credit: Brian Spurlock-USA TODAY Sports ORG XMIT: USATSI-274428 ORIG FILE ID: 20160726_ajw_ss1_190.jpg
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"Resolved, that the flag of the thirteen United States shall be thirteen stripes, alternate red and white; that the Union be thirteen stars, white on a blue field, representing a new constellation,” Adams said during the meeting.

2.) When did Flag Day become a national holiday?

On May 30 1916, President Woodrow Wilson made a presidential proclamation, which officially established Flag Day, according to americaslibrary.gov. It was not until 1949, however, that President Harry Truman signed an act of Congress designating June 14 as Flag Day.

3.) What does Flag Day commemorate?

Flag Day marks the official adoption of the American flag that flies all over the country today. The Flag Resolution of 1777 declared, in part: "Resolved, That the flag of the thirteen United States be thirteen stripes, alternate red and white; that the union be thirteen stars, white in a blue field, representing a new constellation."

4.) How is Flag Day celebrated?

Flag Day is celebrated with parades, essay contests, ceremonies and events sponsored by groups like the National Flag Day foundation, whose goal is to preserve the history and honor to the nation's symbol, Old Glory.

Several celebrated Friday with social media tributes.

5.) Where can I learn more about the American flag?

The United States Code devotes an entire section to the Flag Code, which covers how citizens should respectfully display and treat the American flag.

Read the U.S. Code "Respect for flag" section here.