The general definition of an audit is an evaluation of a person, organization, system, process, enterprise, project or product. Audits are performed to ascertain the validity and reliability of information also to provide an assessment of a system's internal control. The goal of an audit is to express an opinion on the person / organization/system in question, under evaluation based on work done on a test basis. Due to practical constraints, an audit seeks to provide only reasonable assurance that the statements are free from material error. Hence, statistical sampling is often adopted in audits. In the case of financial audits, a set of financial statements are said to be true and fair when they are free of material misstatements - a concept influenced by both quantitative and qualitative factors. Audit is a vital part of Accounting. Traditionally, audits were mainly associated with gaining information about financial systems and the financial records of a company or a business. However, recent auditing has begun to include other information about the system, such as information about security risks, information systems performance