The plumage is iridescent black, glossed purple or green, and spangled with white, especially in winter. The legs are stout and pinkish- or greyish-red. The bill is narrow and conical with a sharp tip; in the winter it is brownish-black but in summer, females have lemon yellow beaks while males have yellow bills with blue-grey bases.
The common starling is 19–23 cm (7.5–9.1 in) long, with a wingspan of 31–44 cm (12–17 in) and a weight of 58–101 g (2.0–3.6 oz). Among standard measurements, the wing chord is 11.8 to 13.8 cm (4.6 to 5.4 in), the tail is 5.8 to 6.8 cm (2.3 to 2.7 in), the culmen is 2.5 to 3.2 cm (0.98 to 1.26 in) and the tarsus is 2.7 to 3.2 cm (1.1 to 1.3 in).
The common starling is largely insectivorous and feeds on both pest and other arthropods. The food range includes spiders, crane flies, moths, mayflies, dragonflies, damsel flies, grasshoppers, earwigs, lacewings, caddisflies, flies, beetles, sawflies, bees, wasps and ants. Prey are consumed in both adult and larvae stages of development, and common starlings will also feed on earthworms, snails, small amphibians and lizards. While the consumption of invertebrates is necessary for successful breeding, common starlings are omnivorous and can also eat grains, seeds, fruits, nectar and food waste if the opportunity arises.
Unpaired males find a suitable cavity and begin to build nests in order to attract single females, often decorating the nest with ornaments such as flowers and fresh green material, which the female later disassembles upon accepting him as a mate. There are normally four or five eggs that are ovoid in shape and pale blue or occasionally white, and they commonly have a glossy appearance.