The principal purpose of mortar is to offer security and cohesion on the stone masonry composition. It helps distribute the load evenly across the stones, boosts their structural integrity, and helps prevent humidity ingress. Be looking out for the Britannica e-newsletter for getting reliable stories delivered right in your inbox. https://digitalasset.us-lax-1.linodeobjects.com/westhillmasonry/Hardscape-Contractors.html