Thanksgiving is a holiday that originated from the Pilgrims' celebration of their first successful harvest in North America in 1621 after their arrival on the Mayflower. The Pilgrims, who sought freedom of religion, faced difficulties in survival and were aided by Native Americans, particularly Squanto, who taught them farming and fishing. Today, Thanksgiving is celebrated with family gatherings, food, and gratitude, although some Native Americans view it as a day of mourning.