1) The world's first credit card was introduced in 1950 by Diners Club.

2) The political system of the People's Republic of China is based on the Communist Party's leadership, with the General Secretary holding significant authority and influence over the country's policies and governance.

3) Michael Phelps, an American swimmer, has won a total of 28 Olympic medals, including 23 gold medals, making him the most decorated Olympian of all time.

4) The highest-grossing film of all time is "Avengers: Endgame," which has earned over $2.79 billion at the global box office.