Thanksgiving Day is a holiday celebrated primarily in the United States and Canada. Thanksgiving is celebrated each year on the second Monday of October in Canada (Columbus Day in the US) and on the fourth Thursday of November in the United States.
The event that Americans commonly call the “First Thanksgiving” was celebrated to give thanks to God for guiding them safely to the New World. The first Thanksgiving feast lasted three days, providing enough food for 13 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.
Thanksgiving in North America had originated from a mix of European and Native traditions. Typically in Europe, festivals were held before and after the harvest cycles to give thanks for a good harvest, and to rejoice together after much hard work with the rest of the community. At the time, Native Americans had also celebrated the end of a harvest season. When Europeans first arrived to the Americas, they brought with them their own harvest festival traditions from Europe, celebrating their safe voyage, peace and good harvest.Though the origins of the holiday in both Canada and the United States are similar, Americans do not typically celebrate the contributions made in Newfoundland, while Canadians do not celebrate the contributions made in Plymouth, Massachusetts.
– From Wikipedia