They decide how you move through the space, where you look, and which parts of the garden you actually visit.
They protect soil: keeping foot traffic off beds prevents compaction.
Watch where worn tracks form across the lawn: they show the routes people naturally take, such as from the back door to the shed, compost bin or vegetable beds.
Solid surfaces such as poured concrete send rainwater running off into drains, carrying pollutants with it.
Mark the route with string, stakes or a garden hose for curves.
Lay the stones on the ground along the route, then walk the path at a normal pace and adjust spacing so each stone falls naturally underfoot.
Excavate to allow for a compacted gravel base of about 4 inches, a 1-inch layer of sand, and the thickness of the bricks or pavers.
Step-by-step advice, charts and free garden calculators at Garden Voila.