A common feature of
trails or
roads--
hiking,
skiing,
paved or otherwise-- that go up or down the side of an
inclined surface.
Since going directly up the side of a mountain is difficult, the path will zigzag back and forth in little chunks of path that are much less steep and move back and forth along the side of the mountain. These are called switchbacks.
Switchbacks leave you walking a much greater distance than a direct route, but in the end make the climb much easier.