Hummingbirds are any of the species of birds belonging to the taxonomic family Trochilidae. They are best known for being the smallest birds, and the only birds that can hover and fly backwards. Its common name comes from the hum its wings make as they flap 12 to 90 times per second as it hovers in mid-air.
Hummingbirds are measure from 2.8 to 3.5 inches, and weigh .7 to .8 ounces.  The plumage (the feathers of a bird that make up their distinctive markings or coloration patterns) of hummingbirds is iridescent and unique; brightly colored The throat gorget the male hummingbirds is a key field mark in shape and color. The picture of Perijá metaltail below shows its unique, iridescent, green gorget.
Long narrow needle-like bills allow them to lick nectar from flowers. The thin, long tongue can be seen in the picture of the Cinnamon-throated hermit below. They have long, narrow, and tapered wings that give them better agility in the air. The shoulder and elbow joints of the wings are very close to the body, allowing each wing to pivot and tilt, which gives hummingbirds their ability to change flight directions and hover. The picture of the Berylline Hummingbird below shows the bird hovering in air. Their tiny legs and feet are not suitable for walking. 
Hummingbirds have a short life span with many not surviving their first year and most dying within three to four years of their birth. The reproduction process begins with the hummingbirds' return to their breeding grounds usually beginning in late March. The male birds return to the breeding grounds about a week before the females. The male birds put on air shows to attract female birds as they arrive, going as high as 49 feet before going into top-speed dives and patterns in the air. The female picks her mate from among those putting on the displays. The male hummingbird may mate with several females.
The female bird weaves her cup-shaped nest with no help from the male bird. The nest, as shown in the picture on the left, is most often built in the branches of tress or shrubs camouflaged with bits of moss. The finished nest is about the size of a ping-pong ball. The female hummingbird lays two white eggs about the size of peas, which are the smallest eggs laid by any bird. Occasionally, a female bird will lay only one egg but rarely does she lay more than two. She sits on her eggs from 18 to 19 days, leaving for only about five minutes every hour. When the babies hatch from their eggs, their mother feeds them by gathering nectar and insects. By the eighth day of life, the babies begin to produce their first feathers. After about three weeks, they leave the nest and completely take care for themselves.
Hummingbirds are mostly found in the South America in the Western Hemisphere. The furthest north they will fly is to Alaska, and furthest south is to Chile. The distribution map on the left indicates the diversity of hummingbirds.  Wooded and forested areas that have lots of flowers are favored habitat for hummingbirds. They live at a variety of altitudes from sea level to fourteen-thousand feet above sea level in the Andes Mountains. 
An adult hummingbird will spend the majority of its life eating, needing to eat about every 10 minutes throughout the day. The hummingbird must eat half to two-thirds of its body weight in food every day. Hummingbirds have the highest metabolism of any animal and use their long beaks to suck nectar and fruit juices, along with catching small insects such as the Ruby-throated Hummingbird in the picture below. Hummingbirds get pollen on their heads and bills while feeding on flowers, just like any other birds do, which transfers it between different flowers and help the plants propagate or reproduce. 
The most unusual behavior of a hummingbird is its flight. As mentioned in the introduction, hummingbirds are the only types of birds that can hover for a long period, change directions almost instantly, and fly backwards. This acrobatic behavior is possible due to the unique design of the wings and joints.
Many birds are aggressive and will ward off intruders away from their terriory. However, hummingbirds can be among the fiercest birds. Regardless of their tiny size, many birders, or bird watchers, have observed hummingbirds successfully repelling much larger birds away from their preferred feeders and flowers. The picture on the left shows two hummingbirds fighting. 
Video of hummingbirds extracting nectar
- Trochilidae Wikispecies. Web. last modified on 29 October, 2015 Author unknown
- Life cycle: Hummingbird Weebly. Web. accessed on January 26, 2016. Unknown author
- Mayntz, Melissa What Is a Hummingbird? About. Web. updated December 28, 2014.
- Foster, Bethney Life Cycle of the Hummingbird eHow. Web. accessed on January, 2016
- Hummingbird Habitats World of Hummingbirds.com. Web. accessed on January 26, 2016. Unknown author