Short answers, pulled from the story.
Socialists define the working class as individuals who have nothing to sell but their own labor power. This category includes all white and blue-collar workers, manual and menial workers of all types. It excludes those deriving livelihood from business ownership or the labor of others.
Karl Marx defined the working class or proletariat as those selling labor power for wages in The Communist Manifesto. He argued these individuals do not own the means of production yet create wealth physically. Marx and Friedrich Engels stated it was the destiny of the working class to displace the capitalist system.
Mike Davis coined the term informal working class for over a billion predominantly young urban people. These individuals exist outside formal global economic structures entirely and try to survive primarily within slums. Members develop worldwide from the 1960s especially across the southern hemisphere.
Diane Reay stresses that university communities are perceived as predominately middle-class social spaces creating barriers. Working-class students often lack cultural capital required for success in these settings. Systemic barriers compound personal struggles when entering academic environments leading to lower retention rates.
Four major industrial states have turned toward semi-market-based governance since 1917 including China, Laos, Vietnam, and Cuba. Large-scale proletarianization occurred globally from 1960 onward generating new working classes in the third world. Countries such as India slowly undergo social change expanding urban working class size.