The amount of information available on-line is proliferating at a tremendous rate. At one extreme, traditional database systems are managing large amounts of structure, well-understood data that can be queried via declarative languages such as SQL. Recently, XML "the eXtensible Markup Language" has emerged as a simple, practical way to model and exchange semistructured data across the Internet, without the rigid constraints of traditional database systems. The thesis studiesa XML languages for the specification of integrated views and the description of query capabilities. This thesis describes work towards unifying and integrating query techniques for traditional electronic sources and XML. First I described XML, semistructured data and then query languages for XML (especially XML-QL). At the end present the software (PFK Design XML Editor) developed by myself.