An overview of topology in ArcGIS
Release 9.3 Last modified October 12, 2010	Print all topics in : "Topologies"

Note: This topic was updated for 9.3.1.

If you have features that are coincident (i.e., share the same location of coordinates, boundaries, or nodes), chances are that using a geodatabase topology can help you better manage your geographic data.

Most users care deeply about the spatial integrity of their feature data, and geodatabase topologies help you to better manage your data integrity. Using a topology provides a strong mechanism to perform integrity checks on your data and will help you to validate and maintain better feature representations in your geodatabase.

Also, many users like to use topologies for modeling numerous spatial relationships between features. These enable support for a variety of analytic operations (e.g., to find adjacent features, to work with coincident boundaries between features, and to navigate along connected features). Topologies enable richer analytic functions in your GIS.

Topological relationships

Topology is the arrangement for how point, line, and polygon features share geometry. Topology is employed in order to

• Constrain how features share geometry. For example, adjacent polygons such as parcels have shared edges, street centerlines and census blocks share geometry, adjacent soil polygons share edges, etc.
  
• Define and enforce data integrity rules (e.g., no gaps should exist between polygons, there should be no overlapping features, and so on).
  
• Support topological relationship queries and navigation (e.g., to navigate feature adjacency and connectivity).
  
• Support sophisticated editing tools (tools that enforce the topological constraints of the data model).
  
• Construct features from unstructured geometry (e.g., to construct polygons from lines).
  

The following topics cover key concepts and ArcGIS support for topology. They also cover a number of common workflows for building and using topologies in ArcGIS. See Topology basics and Topology in ArcGIS for conceptual information.

The process of building a topology from existing data can be summarized in the following steps:

Topology workflow and tasks

Tasks	Links for more information
Design your topology.	See Designing a geodatabase topology.
Create a set of feature classes within a common feature dataset in a geodatabase.	See Working with feature datasets.
If you have existing feature data, load these into your feature classes.	See Loading data into feature classes.
Create the topology using ArcCatalog or geoprocessing tools.	See Using ArcCatalog to create a topology and Using geoprocessing to create a topology.
Build and validate your topology.	See Validating a topology.
Draw and display topologies in ArcMap.	See Drawing and displaying topologies in ArcMap.
Use the ArcMap editor to identify and fix errors.	See Editing a topology.
Manage updates to feature classes and manage dirty areas.	See Validating a topology.
Manage topology within a versioned geodatabase.	See Topology and versioned geodatabases.
Perform many other common editing tasks.	See Common topology tasks.

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