Swallows belong to the family Hirundininae which also includes martins.
There are around 83 species of swallows worldwide.
They are found around the world on all continents except Antarctica.
Swallows live in a wide range of habitats. They are dependent on flying insects and as these are common over waterways and lakes they will frequently feed over these, but they can be found in any open habitat including grasslands, open woodland, savanna, marshes, mangroves and scrubland, from sea level to high alpine areas.
The average lifespan is 3 years in the wild.
Swallows come in a variety of shapes, sizes and colors.
Their body length ranges from about 10–24 centimeters (3.9–9.4 in) and their weight from about 10–60 grams (0.35–2.12 oz).
The most common swallow plumage is glossy dark blue or green above and plain or streaked underparts, often white or rufous.
Swallows have adapted to hunting insects on the wing by developing a slender, streamlined body and long pointed wings, which allow great maneuverability and endurance, as well as frequent periods of gliding.
The long pointed wings have nine primary feathers.
A long tail increases maneuverability, and may also function as a sexual adornment, since the tail is frequently longer in males.
The legs are short, and their feet are adapted for perching rather than walking, as the front toes are partially joined at the base.
Swallows are capable of walking and even running, but they do so with a shuffling, waddling gait.
They have short bills, but strong jaws and a wide gape.
For the most part swallows are insectivorous, taking flying insects on the wing. Across the whole family a wide range of insects are taken from most insect groups, but the composition of any one prey type in the diet varies by species and with the time of year. In addition to insect prey a number of species will occasionally consume fruits and other plant matter.