There are different types of audit, such as financial audit, regulatory audit, operational audit of performances, audit of information systems, environmental audit and others. But basically, we distinguish two types of audit which will be the main focus of attention in this work. External audit, an Internal audit. In most countries, the external auditor from the public sector reports to parliament and, where relevant, the private sector auditor reports to government (e.g. ministry of finance) and/or the public sector external auditor (the supreme audit institution). An efficient system of internal audit is an invaluable source of information for the management of the bank, its supervisors and the quality of the internal control system in that organization.