Presidents’ Day, officially Washington’s Birthday, is a holiday in the
U.S. celebrated on the third Monday of February to honor all persons who served in the office of president of the United States and a federal 
holiday specifically honoring George Washington, who led the
Continental Army to victory in the American Revolutionary War,
presided at the Constitutional Convention of 1787, and was the first president of the United States.

Washington’s Birthday was celebrated on February 22 from 1879
until 1971, when the Uniform Monday Holiday Act moved it to the
third Monday in February, which can occur from February 15 to the 21st.The day eventually also became known as Presidents’ Day^.
(though the placement of the apostrophe, if any, varies) and is
most often an occasion to remember all U.S. presidents, or to
honor Abraham Lincoln‘s and Washington’s birthdays together.