Question

what is focus ? example

Answer 1

Focus is defined as to concentrate on something in particular.Focus is defined as to bring into view. An example offocus is to put all of one's energy into a science project. Anexample of focus is to adjust a microscope to better see a specimen.

Answer 2

It is a point on principal axis of the mirror at which the light rays coming parallel to principal axis, after reflection actually meet or appear to be coming from.
hope this helps u.