Fixed costs describe business expenses that remain constant throughout a financial period. They are costs that are not influenced by the level of productions.
Opportunity cost refers to the forfeited benefits of choosing one option over the others. It is calculated as the cost of the next best alternative.
Variable costs are business costs that vary with the production level. An increase in output increases the variable costs, while a decrease in production means lower variable costs.
An apprenticeship is an example of choosing to get a job right out of high school instead of going to college.