Short answers, pulled from the story.
Discrimination is the process of making unjustified distinctions between people based on the groups, classes, or categories to which they belong or are perceived to belong, usually in a way that deprives them of their legal or human rights. A person need not be actually harmed to be discriminated against; they only need to be treated worse than others for some arbitrary reason.
The term discriminate appeared in English in the early 17th century, from the Latin discriminat-, meaning distinguished between, and ultimately from discernere, corresponding to the English to discern. Before its modern sense became near-universal, discrimination was a synonym for discernment, tact, and culture, as in the phrase taste and discrimination.
Discrimination takes many forms, including age, caste, citizenship, disability, name, political views, race or ethnicity, region, religion, sex and gender, and sexual orientation. Ageism targets the elderly, adolescents, and children, while caste discrimination affects an estimated 250 million people worldwide according to UNICEF and Human Rights Watch.
In a 2002 experiment, Yanis Varoufakis and Shaun Hargreaves-Heap had volunteers play a multiround hawk-dove game in which each player was randomly assigned the color red or blue. Players of the advantaged color consistently played the aggressive hawk strategy against the disadvantaged color, who played the dove strategy, showing discrimination emerging from a purely arbitrary trait.
In the United States, the Civil Rights Act of 1964 broadly prohibits workplace discrimination and the Fair Housing Act of 1968 bars discrimination in the sale or rental of housing. In the United Kingdom, the Equality Act 2010 consolidates, updates, and supplements earlier acts that formed the basis of anti-discrimination law.
Key documents include the Universal Declaration of Human Rights, adopted on the 10th of December 1948, the International Convention on the Elimination of All Forms of Racial Discrimination, adopted on the 21st of December 1965, and the Convention on the Rights of Persons with Disabilities, adopted on the 13th of December 2006. The Convention on the Elimination of All Forms of Discrimination against Women was adopted in 1979 and came into force on the 3rd of September 1981.