Short answers, pulled from the story.
Pop music, or simply pop, is a genre of popular music that originated in its modern form during the mid-1950s in the United States and the United Kingdom. During the 1950s and 1960s it encompassed rock and roll and the youth-oriented styles it influenced.
Pop music usually features repeated choruses and hooks, short to medium-length songs in a basic format such as the verse-chorus structure, and rhythms or tempos that are easy to dance to. The main medium is the song, often between two and a half and three and a half minutes long, with simple beats and melodies and limited harmonic accompaniment.
Rock and pop were roughly synonymous until the late 1960s, after which pop became associated with music that was more commercial, ephemeral, and accessible. Pop is often described as instant singles-based music aimed at teenagers, while rock is cast as album-based music for adults.
Notable pop artists of the late 20th century who became global superstars include Whitney Houston, Michael Jackson, Madonna, George Michael, and Prince. The Oxford Dictionary of Music also cites The Beatles, The Rolling Stones, and ABBA as defining pop performers.
Improved microphone design in the 1940s allowed a more intimate singing style, and 45 rpm records, television, and portable transistor radios reshaped how pop was disseminated and performed. Multi-track recording from the 1960s, digital sampling from the 1980s, music television such as MTV, and later electronic dance music all transformed the genre.
Pop music has been dominated by the American and, from the mid-1960s, British industries, making it something of an international monoculture, though most regions developed their own forms. Japan built a thriving Western-style pop industry, and Latin pop produced record-breaking worldwide hits such as "Macarena" by Los del Río and "Despacito" by Luis Fonsi.
When Billboard compiled a list of the 500 best pop songs in October 2023, it noted there is no real sonic or musical definition to pop. The word "pop" means "popular" first and foremost, so almost any song that becomes popular enough can be considered a pop song.