The sunburst chart is typically used to visualize hierarchical data structures - with part to whole relationships in data depicted additionally. This type of visualization shows hierarchy through a series of rings, where each ring that corresponds to a level in the hierarchy is segmented proportionally to represent its constituent details.
The Sunburst technique is an alternative, space-filling visualization that uses a radial rather than a rectangular layout. In a sunburst chart, the items in a hierarchy are laid out radially, with the top of the hierarchy at the center and the deeper levels farther away from the center. Further, the angle swept out by an item and its color corresponds to some attributes of the data. Technically, an angle encodes a measure while a color encodes a dimension.