Cell motion is crucial for many biological processes, from wound healing to organ formation.  To move, cells must first determine a
preferred direction, and then mechanically move in that direction. In this talk I will first outline the outstanding ability of cells to detect small chemical gradients but adapt to strong variations in the chemical signal.  Then I will describe how cells interact with each other and with the surface. In particular our experimental work focuses on characterizing group migration of cells, and decision making of cells faced with obstacles in surface topography. Our initial results highlight how surface sensing couples into gradient sensing in motile cells.