For all the pins added on the map, there is an option available to cluster them. 
By selecting the Cluster option, the pins will get clustered based on the proximity. It will make a group of nearby pins indicating the number of markers. 
On zooming in to the map, number of pins in the cluster decreases and you get to see individual markers on map. (left image)  
Whereas, when zoomed out, it consolidates the markers into clusters again.
On clicking any cluster (no. of groups), it will show all the pins in spider cluster form.