A problem where you find any answer that follows all the rules.
CSP is a wedding seating chart with drama. Bob avoids Sue. Grandma gets the aisle. Dinner survives.
It shows up in timetables and work schedules. The goal is a valid answer first, not the best one.
Optimization
CSP first looks for an answer that follows all rules. Optimization looks for a better answer.
Heuristic Search
Many CSPs use heuristic search to find a valid answer faster.
Graph Search
A CSP can become graph search when partial answers are treated as states.
KR
KR states the rules clearly, so the system knows which answers are allowed.