Visualization allows overviews to be presented.
Direct manipulation of these visualizations allows rapid feedback, making data exploration a highly interactive process. Visual query languages that work together with direct manipulation increase the expressive power of user interaction. I have recently been working on algorithms to increase the size of datasets that can be interactively explored. I plan to apply these techniques to exploring astronomical, medical, and personal data. The latter includes histories of Web browsing, email, calendar, phone calls, and other document interactions.