This is an archive related to a previous version of ArcGIS Maps for Office. If you need the current version go to http://doc.arcgis.com/en/maps-for-office/.
When a layer contains a large number of point features, showing each feature individually on the map is often not useful. In this scenario, point features often overlap, making it difficult to distinguish between features. Even when they do not overlap, it is usually difficult or impossible to visually extract meaningful information when hundreds or thousands of points are shown all at once.
One approach to resolving this issue is to generate a heat map. A heat map represents the geographic density of point features on a map by using colored areas to represent those points. The areas will be largest where the most points are concentrated together.
The heat map layer is added to the map and the Contents pane. You can turn the heat map on and off, rename, and remove as you would other layers. You can also set the visible range of the heat map, if desired.