When it comes to choosing the best binoculars, it’s good to start by considering what level of magnification you want and what size will be most convenient for your activities. For instance, if you are choosing bird-watching gear, you may need to compromise between magnification and size so that the binoculars are comfortable and easy to wear or carry during long walks.
The two numbers separated by the “x” in a binocular’s description refer to the magnification and the size of the lens (in millimeters). So, 8 x 42 binoculars make the object you're viewing appear eight times closer than it would with your unassisted eyes, and they let in a fair amount of light and fall roughly in the middle of common binocular lens sizes.
You may also want to consider special features or special categories of binoculars, such as night vision binoculars. For wet climates, waterproof binoculars or water-resistant binoculars can be essential.