Data mining is the process of discovering interesting knowledge, such as patterns, association, change, anomalies and significant structures, from large amount of data stored in databases, data warehouse, or other information repositories. Due to the wide availability of huge amounts of data in electronic forms, and the imminent need for turning such data into useful information and knowledge for broad applications including market analysis, business management, and decision support, data mining has attracted a great deal of attention in information industry in recent years. This data mining is only applied for structured data. Structured data means data in formal manner. Sources of this unstructured data are databases. Data mining has been popularly treated as a synonym of knowledge discovery in databases, although some researchers view data mining as an essential step of knowledge discovery.