In GIS, there are two main data models: vector and raster. They are called models because they are not real but are representations of the real world. It is important that we ensure our data is modeling the world as accurately as possible. Vector datasets often have hundreds or thousands of features making it nearly impossible to verify each feature. However, using topology rules, we can let QGIS evaluate the geometry of our datasets and ensure that they are well constructed.

Topology is the relationship between contiguous or connected features in a GIS. Here, you will be introduced to the Topology Checker plugin. This plugin allows you to test topological relationships in your data and ensure that they are modeling the real world accurately. An example of a topological relationship rule is polygons must not overlap. Imagine a country boundaries dataset. It is not possible for a point to be in two countries at once. Therefore, polygons in such a dataset...