These are the famous cables which make it possible for people other than practiced rock climbers to mount the summit.  And this view is what one sees after the grueling climb up Half Dome's shoulder.

No, those are not ants following a sugar trail, they are full size humans.  Some are going up and others are coming down.  Makes for some pretty interesting crossings on the narrow cables.

At any one time about one in ten is frozen to the cables out of fear.  If you're acrophobic at all, this is NOT the place for you.  However, if you can put mind over matter, the climb/haul up the cables is an exhilerating experience.  I highly recommend it for the experientially deprived (or is it depraved?)