Topology in GIS refers to the spatial relationships between adjacent or neighboring features such as points, lines, and polygons. It is a set of rules that define how features share geometry and is used to model spatial relationships between features. Topology is implemented through data structure and is stored in a geodatabase as one or more relationships that define how the features in one or more feature classes share geometry.

Topologies are used to ensure data integrity, validate and maintain better feature representations in a geodatabase, and support a variety of analytic operations such as finding adjacent features, working with coincident boundaries between features, and navigating along connected features. Topology also enables advanced spatial analyses such as adjacency, connectivity, and containment.

Some examples of ways that features can share geometry in a topology include containment, adjacency, and connectivity. Topology is important in GIS because it provides a rigorous, automated method to clean up data entry errors and verify data. It also allows for sophisticated editing tools and feature construction from unstructured geometry.