The quality of a pair of binoculars rests on their crystal clear visibility. Over the last few hundred years, the telescope has been an instrument which has allowed the heavens to come into our doorstep.
A typical bird watcher will tell you that an important feature to look for in binoculars is how tough they are. You buy the telescope and go home, put it up and go to look at the Moon. Many binoculars have eyepieces that fold in and out.
Numbers are used to describe the telescopic strength of the binoculars. So a pair of binoculars that has the number 7x30 stamped onto the casing is a binocular that will magnify any object to seven times its actual size, and has a lens size of 30mm. Earliest documented history shows Hans Lippershey as the first telescope maker including both monocular and binocular variety even though he is not the first person to actually design and produce such a device.
Water-shedding lens protectors have a special coating that allows water droplets to bounce off the surface, which helps reduce repeated cleaning of lens. You don't have to worry about wearing any gloves, which sometimes hampers the focus usage. You may not be planning on getting them wet, but things happen; you might trip and drop them in a mud puddle, take them out on a foggy day, or you might get caught in a freak rain shower.
And don't forget about small children and their fascination with dropping electronic equipment in toilets. You want to look for lightweight, tough, comfortable ones with clarity.