Many consumers prefer online shopping. With the growth of e-commerce websites, retailers tend to fail to attract more and more consumers. Retailers are facing a dynamic and competitive environment. With an increase in globalization and competitiveness, retailers are seeking a better market campaign. Retailers are collecting large amounts of data. This data collected requires proper mechanisms to convert it into knowledge; using this knowledge retailer can make a better business decision. Retail industry is looking strategy wherein they can target the right customers who may be profitable to them. Our project will deal with sales data and customer data that retailers can collect through online shopping websites. Now we will use that data to analyze and finding knowledge using Data mining concepts and methods. Then use this knowledge to study customer segmentation, customer behavior. They will help retailers keep track of customers behavior towards product, so that their marketing strategies are more oriented towards that. Using knowledge from sales data, provide retailers with when they are buying products, how sale affects the sales of the product, which product provide most overall profit, which product provide least overall profit, which products remain unsell, and product associativity, time-series sale analysis of products etc. that will help management in taking strategic decisions and ultimately will increase the overall profit of the retailer.