In a traditional keyword-search system in XML data, a user composes a keyword query, submits it to the system, and retrieves relevant subtrees. In the case where the user has limited knowledge about the data, often the user feels "left in the dark" when issuing queries, and has to use a tryand-see approach for finding information. In this paper, we study a new information-access paradigm for XML data, called "Inks," in which the system searches on the underlying data "on the fly" as the user types in query keywords. Inks extends existing XML keyword search methods by interactively answering keyword queries. We propose effective indices, early-termination techniques, and efficient search algorithms to achieve a high interactive speed. We have implemented our algorithm. The experimental results show that Inks achieves high search efficiency and result quality. Categories and Subject Descriptors H.3.3 [Information Storage and Retrieval]: Information Search a...