The Graph Data Editor is a special version of spreadsheet that allows you to review directly the data that are plotted in the graph. This tool is useful for a variety of analytic applications, such as brushing or other forms of identifying specific data points. It also offers (sometimes) the only way to access data from those graphs, which do not plot raw values but values that have been derived, transformed, or result from specific analytic calculations, as well as values of the fitted functions. It can also be used to add additional plots of a compatible type to an existing graph.
This editor is available from the graph View menu, the graph Format menu, and the general graph shortcut menu (accessible by right-clicking on the background of any graph).