Owls have large forward-facing eyes and ears, a hawk-like beak, and a conspicuous circle of feathers around each eye called the facial disk. Although owls have binocular vision, their large eyes are fixed in their sockets, and they must turn their entire heads to change views.

Owls are far-sighted, and are unable to clearly see anything within a few inches of their eyes. However, their vision, particularly in low light, is excellent.

Many owls can also hunt by sound in total darkness. The facial disc helps to funnel the sound of rodents to their ears, which for better directional location are widely spaced and in some species placed asymmetrically.

Despite their appearance, owls are more closely related to whippoorwills and other nightjars or Caprimulgiformes than to hawks and other diurnal predators (see Falconiformes). Some taxonomists place the nightjars in the same order as owls, as in the Sibley-Ahlquist taxonomy.

Owls' powerful clawed feet and sharp beak let them tear their prey to pieces before eating. Their muffled wings and dull feathers allow them to fly almost silently and unseen. Scientists studying the diets of owls are helped by its habit of disgorging the indigestible parts of their diet, bones, scales, and fur in pellet form. These "owl pellets" are often sold by companies to schools to be dissected by students as a lesson in biology and ecology, because they are plentiful and easy to interpret.

Owl eggs are white and almost spherical, and range in number from a few to a dozen in some owls. Their nests are crudely built and may be in trees, underground burrows or barns and caves.