Tesco is the largest retailer in the UK, with over 7,800 stores worldwide employing over 500,000 people across 12 countries. It began in 1919 as a small market stall in London's East End. Tesco demonstrated early expansionary ambitions by acquiring smaller rival stores throughout the 1950s and 1960s. In 1961, a Tesco store in Leicester entered the Guinness Book of Records as the largest store in Europe, and Tesco opened its first "superstore" in 1968. Today Tesco utilizes technology like its Clubcard rewards program and mobile apps to attract and understand customers better than competitors.