Price fluctuation is a feature of an imperfect market. In an imperfect market, there is a lack of perfect competition, and prices are subject to change due to factors such as supply and demand, production costs, and market power. This is different from a perfect market, where prices are determined solely by supply and demand and are not subject to fluctuations. Supermarkets and common markets are not necessarily imperfect markets, although they can be. Market failure, on the other hand, occurs when a market does not allocate resources efficiently, leading to a loss of social welfare.