Founded in 1919 in London, Tesco is one of the most popular British supermarkets. As one of the largest grocery retailers in the world, it also operates in countries other than the U.K., such as Ireland, Hungary, or Slovakia. In Great Britain and Ireland, there are different types of Tesco stores, depending on size. The biggest one, which can often be bigger than 60,000 square feet, is called Tesco Extra, and commonly known as a “big Tesco” among the public.