Treemap is an interactive graphical technique for visualizing large hierarchical information spaces using nested rectangles in a space filling manner. The size and color of the rectangles show data attributes and enable users to spot trends, patterns or exceptions.

Current implementations of treemaps help explore time-invariant data. However, many real-world applications require monitoring hierarchical, time-variant data. This thesis extends treemaps to interactively explore time series data by mapping temporal changes to color attribute of treemaps. Specific contributions of this thesis include:

· Temporal treemaps for exploring time series data through visualizing absolute or relative changes, animating them over time, filtering data items, and discovering trends using time series graphs.

· The design and implementation of extensible software modules based on systems engineering methodologies and object-oriented approach.

· Validation through five case studies: health statistics, web logs, production data, birth statistics, and help-desk tickets; future improvements identified from the user feedback.