How do I validate a business idea?

How do I validate a business idea is mainly about testing whether a specific customer has an important problem and will take meaningful action toward a proposed solution. A reliable approach is to begin with problem interviews and competitor research, then test positioning, landing pages, prototypes, prices, preorders, pilots, and paid commitments. For example, a service can be tested through a narrowly scoped paid pilot measuring conversion, delivery effort, satisfaction, and repeat interest. The main caution is that compliments, social likes, and survey enthusiasm are weaker evidence than committed behavior. The final output should provide reduced uncertainty around customer, problem, solution, price, channel, acquisition cost, feasibility, and remaining assumptions.