In today's society, data, information and knowledge play crucial role in numerous aspects of human activities. Data refers to individual units of information that are raw and unorganized and are rarely useful alone. Information is derived from data through processing and organizing it in a context, while knowledge is a more abstract concept which represents understanding based on extensive experience with information. Data is present in all human activities which are closely related to usage of computers, involving activities like collecting, storing and analyzing it. By combining different interpretations, data mining can be outlined as the systematic exploration of extensive data repositories through various analytical techniques with the aim to discover and extract useful information.