Data mining is defined as the procedure of extracting information from huge sets of data. Data mining is mining knowledge from data. Data mining is also used in the fields of credit card services and telecommunication to detect frauds. In fraud telephone calls, it helps to find the destination of the call, duration of the call, time of the day or week, etc. It also analyzes the patterns that deviate from expected norms. In the process of data mining various types of classifiers have been used for decision evaluation process. In this paper various approaches have been discussed that can be used for classification of different datasets. On the basis of rules, and trees various classifiers have been reviewed and there process of classification of data has been discussed in this paper.