Looks like water,
But it's heat.
Sits on sand,
Lays on concrete.
People have been known,
To follow it everywhere.
But it gets them no place,
And all they can do is stare.
The answer would be a mirage A mirage is a sort of optical illusion that is caused by the atmospheres condition. Usually seen in very hot areas, which is caused by the refraction of light thats from the sky and by heated air.