When a Layer contains a large number of records rather than displaying each pin individually for clarity the records can be displayed instead as a cluster.

When a Layer's records are clustered they will be dynamically grouped with their surrounding records and the number of records the cluster contains will be displayed in the middle of the cluster.

Each Layer can be configured independently and when multiple Layers are clustered the Layers will be stacked into a single Cluster.  The ring of each cluster will be coloured dependent on the proportion of pins it contains.