Hummingbirds are New World birds that are among the smallest of birds, most species measuring in the 7.5–13 cm (3–5 in) range. They are known as hummingbirds because of the humming sound created by their beating wings which flap at high frequencies audible to humans.

In the wild, hummingbirds visit flowers for food, extracting nectar, which is 55% sucrose, 24% glucose and 21% fructose.[64] Hummingbirds will also take sugar-water from bird feeders. Such feeders allow people to observe and enjoy hummingbirds up close while providing the birds with a reliable source of energy, especially when flower blossoms are less abundant.

A negative aspect of artificial feeders, however, is that the birds may seek less flower nectar for food, and so reduce the amount of pollination their feeding naturally provides.