Look At
Makes an object automatically point at another object.
This is often to make
Lights or
Cameras follow a moving object. It is also useful to control where a character’s eyes will point.
Using Look At
Click the
Look At button on the Modify tab.Click
the object you want to look at the other object and press Enter to confirm your selection.Click
the object to look at and press Enter to confirm your selection.

Each object has a Look At parameter which can be set on the Transform tab of the parameter editor. This shelf tool is simply an interactive way to set those values.
