Step 1: State the core idea in one line.
Social inequality is when society is structured so that certain groups systematically get more of its rewards (money, respect, power) than others.
Step 2: Group the causes under four headings.
Caste based inequality fixes status and occupation by birth, class based inequality follows differences in income and property, gender based inequality limits women's opportunities, and regional inequality leaves some areas underdeveloped compared to others.
Step 3: Note that these causes often overlap.
A person can face more than one form at once, such as a poor, rural, lower caste woman, whose disadvantages from caste, class, gender, and region combine and reinforce each other.
Final Answer:
Social inequality is unequal access to society's resources and status, rooted mainly in caste, class, gender, and regional differences, which often overlap.