1) The first commercially successful video game was "Pong," released in 1972 by Atari.

2) The word "guitar" contains three vowels: U, A, and I.

3) The Danube River, flowing through ten countries in Central and Eastern Europe, is the second-longest river in Europe. It has played a significant role in the cultural and economic development of the regions it traverses and is a popular waterway for river cruises.

4) A single bolt of lightning can heat the surrounding air to temperatures five times hotter than the surface of the sun.