Short answers, pulled from the story.
A quark is an elementary particle and a fundamental constituent of matter. Quarks are permanently confined inside composite particles called hadrons due to a phenomenon called color confinement: as quarks move apart, the strong force between them grows stronger, generating new quark-antiquark pairs rather than allowing isolation.
Murray Gell-Mann and George Zweig independently proposed the quark model in 1964. Gell-Mann's proposal built on his 1961 Eightfold Way classification system; Zweig independently developed the same idea and preferred the name "ace" for the particle.
There are six quark flavors: up, down, strange, charm, bottom, and top. Up and down have the lowest masses and are the most common in the universe; top and bottom were the last to be named, by Haim Harari in 1975, and the top quark was not experimentally confirmed until 1995.
Murray Gell-Mann found the word "quark" in James Joyce's 1939 book Finnegans Wake, in the line "Three quarks for Muster Mark." He adopted it partly because the number three matched how quarks occur in nature. Gell-Mann described this origin in his 1994 book The Quark and the Jaguar.
The top quark was first observed in 1995 by the CDF and DØ teams at Fermilab. Its mass was measured at approximately 173,210 MeV, nearly as large as that of a gold atom, which was much larger than physicists had expected.
Quark-gluon plasma is a theoretical phase of matter in which extreme heat causes quarks and gluons to move freely rather than remain bound inside hadrons. A fully free quark-gluon plasma has never been achieved; CERN attempted it in the 1980s and 1990s, and the Relativistic Heavy Ion Collider has since produced evidence for a liquid-like quark matter with nearly perfect fluid motion.