Market power
There are several forms of market structures extending from a monopoly where there is a single seller of a commodity to perfect competition where there are many sellers each of whom has an insignificant share of the total market.
Between the two extremes of monopoly and perfect competition there exists many different types of market structures to which the term imperfect competition is applied.
There may be imperfect competition which is very close to monopoly, or a form of imperfect competition close to perfect competition.
Duopoly means that the market consists of two sellers.
Oligopoly means that there are few sellers.
Market Structures
| Perfect Competition | Monopolistic Competition | Oligopoly | Monopoly | |
| Number of Firms | Many | Many | Few | One |
| Types of Product | Homogenous | Differentiated | Homogenous/Differentiated | — |
| Forms of Competition between Producers | ————- | Non – price Competition | Price/non-price Competition | — |
| Availability of Information | Perfect Information | Imperfect knowledge | Imperfect knowledge | Imperfect knowledge |
| Barriers to entry | Free entry | Free Entry | Entry restricted | Entry restricted |
| Control over Price | Price Taker | Price searcher | Price searcher | Price searcher |