A birdfeeder, bird table, or tray feeder is a device placed outdoors to supply bird food to birds (bird feeding). The success of a bird feeder in attracting birds depends upon its placement and the kinds of foods offered, as different species have different preferences.

Most bird feeders supply seeds or bird food, such as millet, sunflower (oil and striped), safflower, nyjer seed, and rapeseed or canola seed to seed-eating birds.

Bird feeders often are used for birdwatching and many people keep webcams trained on feeders where birds often congregate, with some even living just near the bird feeder.

Seed feeders are the most common type of feeders. They can vary in design from tubes to hoppers and trays. Sunflower seeds or mixed seeds are popular for use in these feeders and will attract many songbirds such as cardinals, finches, and chickadees. Black oil sunflower seeds are especially popular with bird enthusiasts. The outer shell of the black oil sunflower seeds are thinner and easier to crack than other types of sunflower seeds. In addition, the kernel is larger than the striped or white sunflower seeds. Black oil sunflower seeds also contain a large amount of fat; therefore they are especially good to use in the winter. Most bird feeders are designed to dispense sunflower-sized foods, but there are specialty "finch feeders" with smaller openings to dispense the tiny Guizotia abyssinica (Niger seed), which is a favorite of smaller finches.

Seed feeders are mainly squirrel proof, tube-like or hopper. Due to the need of keeping squirrels away from the bird food, manufacturers have created different defense mechanisms that may deter squirrels from getting close to the seed. Some seed feeders come with weight sensitive technology which shuts off the access to the seed ports whenever a heavy weight is detected (as most squirrels are heavier than birds). Birds can still feed as they weigh less and the ports remain open under their weight. Other seed feeders are designed to be mounted on poles as it is believed that squirrels reach seed feeders more easily from trees than from poles. The simplest type of squirrel proof feeder is a tube-like feeder surrounded by a metal cage. These feeders also offer protection from larger and more aggressive birds. Tube seed feeders are primarily made of clear plastic tubes with plastic or metal caps, bases and perches. Hopper bird feeders look like a house and attract a wide range of birds such as finches, cardinals, blue jays, sparrows and titmice.

Hummingbird feeders, rather than dispensing seed, supply liquid nourishment to hummingbirds in the form of a sugar solution. The solution is normally 4 parts water to 1 part white sugar. Only pure refined white cane or beet sugar should be used, according to experts:

Hummingbird feeders usually have red accents or red glass to help attract hummingbirds. The sugar mixture is sometimes colored with red food coloring to attract birds, though this is not necessary if the feeder itself is red, and may actually be harmful to the birds. Yeasts tend to grow in hummingbird feeders and spoil the solution, so they must be refreshed frequently and kept very clean to avoid harm to the birds. See the article on hummingbirds for more details. Ants and other insects are also attracted to hummingbird nectar. Smearing petroleum jelly on the stem or cap of the feeder (away from the perch or flower part where the bird may come into contact with it) may prevent the ants from crawling to the feeder. When placing a hummingbird feeder, the feeder is best suited 15 to 20 feet from windows; 10 to 15 feet from the nearest cover, like shrubs or bushes; and in an open area that receives partial sun, so that hummingbirds can move from nectar source to nectar source.

Hummingbird top-fill feeders are popular among bird lovers because they are easy to fill and clean and also because they do not need to be turned upright which means that there are less chances that the nectar is spilled. The sports bottle top-fill hummingbird feeders have the design of a sports bottle, with a mechanism that works similarly to such a bottle. With this type of feeder, one has to push down the plastic container in order to close the nectar reservoir and then to unscrew the cap and pour the nectar. After the cap is replaced, the body of the nectar reservoir can be pulled up. This type of bird feeder has the advantage that the feeder does not need to be turned upside down to be refilled and which results in less nectar wasted by spilling. The traditional top-fill hummingbird feeders are one of the most popular types. There is also a plunger type of top-filling hummingbird feeder which comes with a small plunger in the container that creates the vacuum seal when the lid is tightened and the nectar will start flowing only when the lid is sealed correctly to the feeding ports.