What is a 'Resource' in CO? | SAP-FICO

Resources are goods / services, consumed by CO objects like cost centre / internal order / WBS element, which are supplied (internally or externally) to an organization in order to produce business activities. The resources are used only in planning and not for tracking the actual.   
There are three types of resources:   
•    Type B (used in base planning object)   
•    Type M (refers to a material)   
•    Type R (exists only in CO-OM)