A Pivot Table is a table of data that can pivot or rotate around a specific point in that data, whether it be a data type or category.

Otherwise called crosstab, PivotTable, PowerPivot, DataPivot, DataPilot and other names. Pivot tables can combine data or provide summary views that may be powerful for analysis purposes. They may also allow drill-down from the summary to show details underlying a selected entry.

See the MS Office KB or wikiHow for Excel usage.