Thanksgiving, or Thanksgiving Day, is a holiday celebrated in the United States on the fourth Thursday in November. It has officially been an annual tradition since 1863, when, during the Civil War, President Abraham Lincoln proclaimed a national day of "Thanksgiving and Praise to our beneficent Father who dwelleth in the Heavens", to be celebrated on Thursday, November 26. As a federal and popular holiday in the U.S., Thanksgiving is one of the major holidays of the year. Together with Christmas and the New Year, Thanksgiving is a part of the broader holiday season.

The event that some Americans commonly call the "First Thanksgiving" was celebrated by the Pilgrims to give thanks to God for guiding them safely to the New World. The first Thanksgiving feast lasted three days, providing enough food for 53 Pilgrims and 90 Native Americans. The feast consisted of fish (cod, eels, and bass) and shellfish (clams, lobster, and mussels), wild fowl (ducks, geese, swans, and turkey), venison, berries and fruit, vegetables (peas, pumpkin, beetroot and possibly, wild or cultivated onion), harvest grains (barley and wheat), and the Three Sisters: beans, dried Indian maize or corn, and squash. The New England colonists were accustomed to regularly celebrating "thanksgivings"—days of prayer thanking God for blessings such as military victory or the end of a drought.