Storing the enormous amount of raw data into database will not be able to provide the meaningful information, rather those data should be analyzed and the hidden knowledge must be extracted by the use of datamining which is a main phase of the knowledge discovery process. This paper aims to explore information related to various datamining techniques and their relevant applications. Specifically it will elaborate the information regarding preprocessing and post processing steps in datamining techniques such as association rule mining, clustering, classification, neural networks, visualization and their applications such as e-services, education, business, security and agriculture will be discussed along with issues and challenging tasks. © IAEME Publication.