Birdwatching or birding is the observation of bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s as a recreational activity. It can be done with the naked eye, through a visual enhancement device like binoculars

Binoculars

Binoculars, field glasses or binocular telescopes are a pair of identical or mirror-symmetrical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects...

 and telescopes, or by listening for bird sounds. Birding often involves a significant auditory component, as many bird species are more readily detected and identified by ear than by eye. Most birdwatchers pursue this activity mainly for recreational or social reasons, unlike ornithologists

Ornithology

Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...

, who engage in the study of birds using more formal scientific methods.
The term birdwatching was first used in 1901; bird was introduced as a verb in 1918.