Short answers, pulled from the story.
Racism is the belief that groups of humans possess different behavioral traits tied to inherited attributes and can be ranked by the superiority of one race or ethnicity over another. It may also mean prejudice, discrimination, or antagonism directed against people of a different ethnic background.
The word racism came into widespread usage in the Western world in the 1930s, when it was used to describe the social and political ideology of Nazism. The Oxford English Dictionary cites the shorter term "racism" in a quote from the year 1903, while the earlier term "racialism" appears in a 1902 quote.
Scientific racism was an attempt to provide a racial classification of humanity, such as Johann Blumenbach's 1775 division of people into five groups by skin color. The term is a misnomer because no actual science backed its claims, and human genome research indicates that race is not a meaningful genetic classification of humans.
Institutional racism is racial discrimination by governments, corporations, religions, educational institutions, or other large organizations with power over many lives. Stokely Carmichael is credited with coining the phrase in the late 1960s, defining it as an organization's collective failure to serve people properly because of their colour, culture, or ethnic origin.
The Nazi party, which seized power in the 1933 German elections, graded humans from pure Aryan to subhuman and placed Jews at the bottom as unworthy of life. Approximately six million Jews were killed in the Holocaust, along with 2.5 million ethnic Poles, 0.5 million ethnic Serbs, and between 0.2 and 0.5 million Romani.
Limpieza de sangre, meaning cleanliness of blood, was a doctrine formulated by Catholic Spaniards after the fall of Granada in 1492 to block the upward mobility of converted New Christians. It gave rise to the idea of aristocratic blue blood, and in Portugal the legal distinction between New and Old Christian only ended through a decree by the Marquis of Pombal in 1772.
The Universal Declaration of Human Rights, adopted in 1948, recognized rights without distinction as to race. The United Nations defines racial discrimination through its 1965 International Convention as any distinction or preference based on race, colour, descent, or national or ethnic origin that impairs human rights on an equal footing.