An agent is a person employed to act on behalf of another person called the principal. Anyone of age and sound mind can appoint an agent, and anyone can be an agent regardless of age or mental capacity. There are two types of agents: sub-agents, who are appointed by other agents, and co-agents, who are appointed by the agent with the principal's authority to act on the principal's behalf. Agents have rights including the right to retain amounts owed by the principal, stop goods in transit if personally liable, claim agreed remuneration, indemnity from the principal, and lien over goods. Agents' duties include conducting business as directed, using reasonable care and skill, rendering accounts, communicating difficulties, not dealing