1) 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.

2) The Cuban Missile Crisis in 1962 brought the United States and the Soviet Union to the brink of nuclear war during the Cold War.

3) The highest-grossing concert tour of all time is U2's "360° Tour," which earned over $735 million in ticket sales.

4) The term "cloud computing" refers to the delivery of computing services, including storage, databases, and software, over the internet rather than on a local server.