Definition
In OpenStreetMap (OSM), a relation is a way to group together multiple elements, such as nodes, ways, and other relations, to create a more complex and meaningful representation of a geographic feature.
For example, a road network can be represented as a relation that groups together individual ways (segments of roads) to create a complete network. Similarly, a river system can be represented as a relation that groups together individual ways (segments of the river) to create a complete network.
Relations can also be used to represent other types of features, such as public transit routes or hiking trails. For instance, a public transit route can be represented as a relation that groups together individual ways and stops to create a complete route. Similarly, a hiking trail can be represented as a relation that groups together individual ways and points of interest to create a complete trail map.
Relations in OSM are identified by a unique ID number and can be created and edited using OSM editors such as JOSM or iD Editor. They are a powerful tool for creating complex and detailed representations of geographic features, and they allow OSM data to be used in a wide range of applications, from navigation tools to disaster response systems.
In summary, relations in OpenStreetMap are a way to group together multiple elements to create more complex and meaningful representations of geographic features. Examples of relations include road networks, river systems, public transit routes, and hiking trails.
