Step-by-step explanation:
When two objects of different temperature are held together by touching each other then there will be flow or transfer of heat from hotter object to cooler object. This process of exchange of heat is known as conduction.
For example, a metal spoon placed in a hot coffee mug shows flow of heat from coffee to the spoon.
Thus, we can conclude that a condition which must exist in order for conduction to occur between two substances is that the objects must be touching each other.