In this Research paper, we present an overview of research issues in web mining. We discuss mining with respect to web data referred here as web data mining. In particular, our focus is on web data mining research in context of our web warehousing project.We have categorized web data mining into three areas; web content mining, web structure mining and web usage mining. We have highlighted and discussed various research issues involved in each of these web data mining category. We believe that web data mining will be the topic of exploratory research in near future.