1. Perfect Competition Market where there are numerous buyers and sellers
No one entity or thing can affect the prices 
Four conditions must exist to create this situation:
Large Market
Similar Products
Easy Entry and Exit
Obtainable Information

2. Imperfect Competition
Monopoly
Oligopoly
A single seller controls the good/service and directly determines the price
Characteristics
Single Seller
No substitutes
No entry
Almost complete control of market price
A few suppliers that exercise some control over price dominance
Characteristics
Domination by a few sellers
Barriers to entry
Identical or slightly different products
Nonprice competition
Limited control over price

3. Monopolistic Competition
Large numbers of sellers offer similar/slightly different products
Characteristics
Numerous sellers**
Relatively easy entry**
Differentiated products**
Non-price competition
Some control over price
**Differences of Oligopoly and Monopolistic Competition