Internal and External auditing
External auditing is the process whereby an independent auditor examines an organization's financial statements and accounting records in order to express an opinion that conveys reasonable but not absolute assurance - as to the truth and fairness of the statements and the accountant's adherence to Generally Accepted Accounting Principles (GAAP), in all material respects.
Internal auditing is an examination in which management, and not the external public, is the main beneficiary. It is carried out usually by auditors employed by the company, but sometimes by external service providers. The internal auditor's role is broader, and basically depends on what kind of assurance management wants. It usually certifies the efficiency and effectiveness of processes, departments, projects or internal controls. The Institute of Internal Auditors is generally accepted as the custodian of Internal Auditing best practice.