A cost object is anything for which cost data are desired-including products, customers, jobs, and organizational sub units. For the purpose of assigning cost to cost objects, costs are classified as:
Direct Cost: A cost that can be easily and conveniently traced to a specified cost objects.
Indirect Cost: A cost that cannot be easily and conveniently traced to a specified cost objects.
A common cost is a cost that is incurred to support a number of cost objects but cannot be traced to them individually.
A particular cost can be direct or indirect depending on the cost object.