average fixed cost (AFC)   total fixed cost divided by the quantity produced
average physical product(APP)  output per unit of resource
average total cost (ATC)  cost divided by the total output
average variable cost (AVC)  total variable costs divided by the quantity produced
constant returns to scale  unit costs remain constant as the quantity of production is increased and all resources are variable
diseconomies of scale  the increases of unit costs as the quantity of production increases and all resources are variable
economies of scale  the decrease of unit costs as the quantity of production increases and all resources are variable
law of diminishing marginal returns  when successive equal amounts of a variable resource are combined with a fixed amount of another resource, marginal increases in output that can be attributed to each additional unit of the variable resource will eventually decline
long-run average total cost (LRAC)  the lowest-cost combination of resources with which each level of output is produced when all resources are variable
marginal cost (MC)  the additional costs of producing one more unit of output
marginal physical product (MPP)  the additional quantity that is produced when one additional unit of a resource is used in combination with the same quantities of all other resources
minimum efficient scale (MES)  the minimum point of the long-run average cost curve; the output level at which the cost per unit of output is the lowest
scale  size; all resources change when scale changes
short-run average total cost (SRATC)  the lowest-cost combination of resources with which each level of output is produced when the quantity of at least one resource is fixed
total costs (TC)   the sum of total variable and total fixed costs
total fixed costs (TFC)   costs that must be paid whether a firm produces or not
total physical product (TPP)   the maximum output that can be produced when successive units of a variable resource are added to fixed amounts of other resources
total variable costs (TVC)  costs that rise or fall as production rises or falls