Lattice is a powerful deformer tool that you can use to deform the shape of any mesh in Maya. The lattice will surround the object on which you apply it. The lattice will have Lattice points, which are the control points that when dragged, deforms the base object's vertices, so that the shape of the base object itself gets deformed. The deformation of the base objects vertices in Maya will be in accordance with, those vertices' distance from the lattice point that we are moving.

Activating the control points (lattice points) can be a little tricky if you are new to Maya. In order to activate the lattice, what you need to do is select the lattice and right click on it (don't release the mouse yet) and choose 'Lattice Point' from the menu that appears. But the basic problem is that since the lattice always surrounds the base object, when you try to select the lattice, in most cases the base object gets selected in Maya. You can overcome this difficulty in selecting the lattice by means of two ways.