ExQueX is an interactive system for exploring and querying XML documents. The exploration is done by searching, ranking and filtering, and it enables users to discover relationships that exist in a given document. The results of the exploration can be used either directly as tree queries or as building blocks in the process of formulating more complex queries. The latter is done by formulating an abstract tree query, whose edges represent relationships that are resolved by using concrete results from the exploration phase. ExQueX facilitates fast and clear understanding of both the contents and complex structures of XML documents.