Data mining refers to extracting or \"Mining\" knowledge from large amounts of data. Data mining should have been more appropriately named \"Knowledge mining from data\". Data mining is also called as Knowledge Discovery from Data (KDD). Knowledge discovery as a process consists of the following steps: data cleaning, data integration, data selection, data transformation, data mining, pattern evaluation and knowledge presentation. A fuzzy rule-generation method for pattern classification problems with classification priority. The assumption is that a classification priority is given a priori in relation to other classes.