Perfect Competition
Plain definition
A market structure with many small sellers, identical products, free entry and exit, and full information — so each firm is a price taker.
In economics
In perfect competition, no single firm can influence the market price; each faces a horizontal demand curve at the market price, producing where P = MC. Firms earn only normal profit in the long run, because any economic profit attracts entry that drives price down to minimum ATC.
Example
Agricultural commodity markets like wheat approach perfect competition: thousands of farmers sell an identical product and accept the going market price.
Perfect competition is confused with 'fierce rivalry.' It describes a structure with so many sellers that rivalry is impersonal — no firm advertises or undercuts strategically. Real markets that look competitive (smartphones, airlines) are usually oligopolies or monopolistic competition, not perfect competition.