i. Incremental Costs: These are additional costs incurred when a business decision leads to an increase in the level of activity. For example, extra labor or materials required to fulfill a special order.

ii. Differential Costs: The difference in total costs between two or more alternative decisions. It represents the change in costs when choosing one option over another.

iii. Avoidable and Unavoidable Costs:

• Avoidable Costs: Costs that can be eliminated if a particular activity is stopped. These are relevant for decision-making.
• Unavoidable Costs: Costs that will still be incurred regardless of the decision made. These are not relevant for decision-making.

iv. Committed Costs: Costs that the company has already committed to, and which cannot be altered in the short term. They are not relevant to future decision-making.

v. Sunk Costs: Costs that have already been incurred and cannot be recovered. These costs are not relevant to future decisions.

vi. Opportunity Costs: The potential benefits or income lost when choosing one alternative over another. It represents the value of the next best alternative that is foregone.