Fixed Costs (FC): costs not dependent on amount produced (eg: rent, utility bills).
Variable Costs (VC): costs that do depend on how much is produced (raw materials,
Perfectly competition: market structure with many firms that produce homogeneous goods and have perfect knowledge (eg: buyers can find out how much each firm in this market structure is charging for the same good through internet).
Monopolistic competition: Like perfect competition but goods are SLIGHTLY DIFFERENTIATED.
Oligopoly: many firms but only a few firms DOMINATE the market.
Monopoly: where only one firm opertaes in the industry (ie: the firm is the industry).
Natural monopoly: industry only able/profitable to support one firm (usually railway/utitility firms such as gas/water).
Monopsony: only one buyer in the market but many sellers.