Short answers, pulled from the story.
Nobility is a hereditary social class ranked just below royalty, typically carrying specific legal rights, obligations, and titles. Being wealthy or influential cannot by itself make a person noble, and not all nobles have been wealthy; the concept of the poor nobleman is described as almost as old as nobility itself.
Blue blood translates the Spanish phrase sangre azul, describing the Spanish royal family and high nobility who claimed Visigothic descent in contrast to the Moors. The idiom derives from the visible blue veins beneath the pale, untanned skin of aristocrats who did not perform outdoor labour, as recorded in English by 1811 in the Annual Register.
Seize quartiers, or sixteen quarterings, was the requirement that a French nobleman demonstrate exclusively noble ancestry extending back five generations, meaning all sixteen great-great-grandparents were noble. In the final years of the ancien regime, the old landed nobility pushed to restrict certain offices and orders of chivalry to men who could prove this lineage.
The Kingdom of Ndongo (c. 1518-1682) had a structured hierarchy of sobas who governed territories called murinda and paid tribute to the Ngola, or king. The system included titles parallel to European ranks: di-kanda for count, mvunda for duke, and mbanza for baron, using vocabulary from the Mbundu language.
India abolished all noble privileges through the Twenty-Sixth Amendment to its constitution, passed in 1971. Brazil discontinued its nobility with the proclamation of the First Brazilian Republic in 1889, at which point 1,211 noble titles had been acknowledged during the Empire of Brazil.
The oldest continuously held noble title in Chinese history belonged to the descendants of Confucius, originally the title of Duke Yansheng. It was renamed the Sacrificial Official to Confucius in 1935 by the Republic of China and is currently held by Kung Tsui-chang.