The name "pilgrim" refers to one who journeys for religious reasons. Those first pilgrims who landed on Plymouth Rock on Dec. 11, 1620, were originally residents of England, but they left for the New World so they could have the freedom to practice their religion without interference from the king.
Following the separation of England from the Roman Catholic Church, England's reigning monarch became the head of the new Church of England and had authority over both church doctrine and practice. The pilgrims were part of a group known as the Separatists, and they disagreed with the structure and beliefs of the Church of England.
The pilgrims left for the New World upon the famed ship known as the Mayflower. When they arrived, they encountered members of the Wampanoag Native American people. These natives taught the pilgrims how to plant and harvest food, and the pilgrims celebrated their success with the natives by holding the first Thanksgiving celebration in 1621. This first Thanksgiving meal consisted of roasted wild fowl of different sorts, sea bass, deer meat, cornmeal and other food items.
Despite the celebratory nature of the event, it occurred after a harsh time for the pilgrims. Only half of those who came on the Mayflower were alive to celebrate it.