1) In Norse mythology, the Valkyries are divine maidens who serve Odin, the chief god. They are responsible for selecting warriors worthy of entering Valhalla and escorting them to the afterlife. They are often depicted as powerful and beautiful figures, riding winged horses and wielding spears.

2) The first successful mass-produced personal computer, the IBM PC, was introduced in 1981 and played a significant role in popularizing the use of computers in homes and offices.

3) Mount Everest, located in the Himalayas, is the highest mountain on Earth, reaching a peak elevation of 29,032 feet (8,848 meters).

4) In recent years, climate change has become a significant global concern, leading to increased efforts to reduce carbon emissions, promote renewable energy, and implement sustainability measures.