Topologies store three sets of parameters—rules, ranks, and a cluster tolerance. When editing a geodatabase, you will not typically need to modify these parameters, but you will need to be aware of them, especially the rules.

Topologies also maintain a feature layer that stores dirty areas, errors, and exceptions. You use these to maintain the quality of data in your topology.

Instead of storing topological information for all features, the topology discovers those relationships when the information is requested, such as when you are editing using the Topology Edit tool. The topology stores some feature layers that let it efficiently track the places where the topology may have been violated during editing—dirty areas—and features that were found to violate topology rules after validation—error features. Certain errors may be acceptable, in which case the error features are marked and stored as exceptions

Topology has historically been viewed as a spatial data structure used primarily to ensure that the associated data forms a consistent and clean topological fabric. With advances in object-oriented GIS development, an alternative view of topology has evolved. The geodatabase supports an approach to modeling geography that integrates the behavior of different feature types and supports different types of key relationships. In this context, topology is a collection of rules and relationships that, coupled with a set of editing tools and techniques, enables the geodatabase to more accurately model geometric relationships found in the world.

Learn more about topology by visiting Environmental Systems Research Insitute (ESRI)