Express Agency:
Express agency is created by either an oral or a written agreement between the principal and the agent. It indicates their express intent for this representational status.In real estate, agency is normally created by either a written listing agreement with a seller, or a buyer agency agreement with a buyer. Some states allow verbal agreements, but most do not.
Implied Agency:
It is also possible to create an agency relationship by the actions of the parties. If a real estate agent takes on responsibilities that are normally those of an agent, but hasn't signed an agency agreement, she may still be considered an agent via implied agency. By the same token, if the customer asks the agent for advice or actions that are normally those in agency, then an implied agency could be created.Some states have created specific legislation that states that no agency can exist without a written agency agreement. This helps to avoid accidental implied agency.

