1. A system for managing online documents, the system comprising: a sheet data store configured to store a plurality of sheets, wherein each sheet includes a set of rows, and wherein each row includes a set of columns; an interaction monitoring engine configured to monitor interactions by users with the plurality of sheets; an interaction data store configured to store records of the interactions monitored by the interaction monitoring engine; a sheet metadata data store configured to store sheet metadata representing relationships between sheets of the plurality of sheets; a collaboration graph generation engine configured to generate a collaboration graph that represents relationships between the sheets and the users based on the interaction records and the sheet metadata; a collaboration graph analysis engine configured to analyze vertices the collaboration graph for similarities; a visualization generation engine configured to generate one or more visualizations of collaboration graphs generated by the collaboration graph generation engine; and a collaboration graph data store configured to store a plurality of collaboration graph versions generated over time; wherein the visualizations include an animation that shows changes in the collaboration graph versions over time.
1. A system for managing online documents, the system comprising: a sheet data store configured to store a plurality of sheets, wherein each sheet includes a set of rows, and wherein each row includes a set of columns; an interaction monitoring engine configured to monitor interactions by users with the plurality of sheets; an interaction data store configured to store records of the interactions monitored by the interaction monitoring engine; a sheet metadata data store configured to store sheet metadata representing relationships between sheets of the plurality of sheets; a collaboration graph generation engine configured to generate a collaboration graph that represents relationships between the sheets and the users based on the interaction records and the sheet metadata; a collaboration graph analysis engine configured to analyze vertices the collaboration graph for similarities; a visualization generation engine configured to generate one or more visualizations of collaboration graphs generated by the collaboration graph generation engine; and a collaboration graph data store configured to store a plurality of collaboration graph versions generated over time; wherein the visualizations include an animation that shows changes in the collaboration graph versions over time. 3. The system of claim 1 , wherein the visualizations include a two-tier visualization that includes: a first level that comprises a plurality of sheet icons; and a second level that comprises a plurality of user icons.