Binoculars: What do the numbers mean. i.e. 12 X 30.?

Question

Binoculars: What do the numbers mean. i.e. 12 X 30.?

Answer 1

Hey!  The first number is the magnification 12x  and the second number is the diameter of the front lens 30mm

If you want high magnification 12x you need a large lens at the front to gather plenty of light, more like 50mm or 60mm

Answer 2

The first poster got it right, just like to add, watch for that magnification.  Anything greater than a 10x is almost impossible to handhold, unless it has IS(Image Stabilization).  

The drawback of large magnification is also field of view, the larger the magnification the narrower your field of view is.  So, if you're intending on using this for say, birding, then you want something with a large field of view.