U musta seem cameras in which the lens move forward or retract to original, when the sound of a small motor and other mechanical parts can be heard... yah... that's when optical zooming is done.
There are 2 types of conventional zooming
1. Digital zoom, in which software in camera extrapolate(mathematically guess) the pixels and enlarge the scene. It is same as scaling in image editors like Photoshop. As a result, it is not the original picture, but a "guessed" one and is inferior in quality as it's just scaling, no new pixels added, the same old ones r spread apart!!!
2. Optical zoom, in which the hardware(replace with "lens") are actually aligned to & fro to enlarge the view in the camera. Technically the focal lengths of the lens are varied here. So this gives us as close a picture to the real view as possible and is definitely of better quality. Unlike digital zoom, optical zoom enlarges the subject without sacrificing resolution. It is the true zoom.
The 1x, 2x are the magnifications achieved. [FONT=Verdana, Arial, Helvetica, sans-serif]It describes the lenses ability to multiply the size of a subject between its minimum and maximum focal lengths.[/FONT] 2x means the picture dimensions are multipiled by 2.
Optical zoom wiki