1. Fixed
2. Variable costs
   1. rise as output rises
   2. at output = 0 there are no variable costs
3. total cost
   1. add
      1. fixed cost
      2. variable costs
4. Marginal cost
   1. TC - TC of producing one less unit
   2. MC falls
      1. if easier to produce next unit
      2. Increasing Marginal Returns
   3. MC is unchanged
      1. same cost to produce next unit
      2. constant marginal return
   4. MC rises
      1. more costly to produce next unit of
      2. Subtopic 2
5. Average costs
   1. cost divided by quantity
   2. types
      1. Fixed (AFC)
      2. Variable (AVC)
      3. Total (AC)