A dry stone wall is one built entirely or mainly without the use of mortar.  It relies on its strength and durability by the careful placing of stones so that each one is securely locked into position. 

The United Kingdom has a wide variety of dry stone walls, with distinct regional differences in style of building.  A dry stone wall in Cumbria built from flat slate will appear very different to a gritstone wall in The Dark Peak in Derbyshire.  

However, the method of construction is basically the same, and a well-built wall will last for several generations with the minimum of maintenance.   As boundaries, dry stone walls have distinct advantages over hedges, which need constant upkeep and fences which will rot in 15-20 years and eventually need replacing. 

Dry stone walls not only add significant aesthetic quality to our landscapes but are a haven for a wide variety of complex plant, animal and insect species.  It is quite common to find toads living in dry stone field walls!