The advancement of information communication technology has generated a large amount of data from different sources, which may be stored in different geological locations. Each database may have its own structure to store data. Mining multiple data sources  distributed at  different geological locations to discover useful patterns are critical important for decision making. In particular, the Internet can be seen as a large, distributed data repository consisting of a variety of data sources and formats, which can provide abundant information and knowledge.

Data from different sources may seem irrelevant to each other. Once information generated from different sources is integrated, new and useful knowledge may emerge. Here is an excellent example of how an organization to utilize mining data from different data sources to obtain  profound information, which cannot obtain from an individual source.

Data mining is born as a particular step of a process defined in literatureas Knowledge Discovery in Databases (KDD). Due to the centrality acquired by Data Mining task within this process, nowadays Data Mining isused as synonym for Knowledge Discovery, also known as Knowledge Discovery and DataMining.