完全競争

A perfectly competitive market has several defining characteristics: many buyers and sellers with no single participant controlling price, identical products across all firms, free entry and exit without barriers, and perfect information available to all participants. These conditions ensure no firm can influence market price, making them price takers who accept prices determined by supply and demand forces.

Firms are price takers because the market has many buyers and sellers, and no single firm is large enough to influence price. The market price is determined entirely by overall supply and demand forces. Since products are identical and buyers have perfect information, individual firms must accept the prevailing market price or lose customers to competitors.

Free entry and exit means new businesses can start selling or existing firms can leave without facing financial, legal, or technological barriers. This keeps the market dynamic and competitive, ensuring a level playing field for all competitors. The ability to enter or exit freely prevents any firm from maintaining long-term competitive advantages.

Perfect information means all buyers and sellers have complete knowledge about prices, quantities, and market conditions. This enables participants to make well-informed decisions and promotes healthy competition. When everyone has equal access to market data, no participant can exploit information asymmetries to gain unfair advantages.

Homogeneous, or identical, products mean consumers have no preference for one supplier over another based on product differences. This eliminates brand loyalty or product differentiation as competitive factors. When all products are identical, price becomes the primary competitive variable, reinforcing the price-taker role of firms.

Perfect competition is a purely theoretical concept that no real-world market fully achieves. However, it serves as a benchmark for economists to measure how well markets function. The agricultural sector for staple crops like wheat comes closest to perfect competition, with many farmers selling identical products, widely available price information, and relatively easy market entry and exit.

In perfect competition, individual firms face a perfectly elastic demand curve because they are price takers. The demand curve perfectly competitive market appears as a horizontal line at the market price, reflecting that firms cannot raise prices without losing all customers. This contrasts with other market structures where firms have some pricing power.