A suet feeder is used to attract birds, typically woodpeckers, away from trees and your house. The feeder is usually a metal cage structure that holds the suet bricks. The bricks or cakes are square shaped blocks usually made up of a mixture of things, including suet (or rendered beef fat) as a primary ingredient. Other ingredients in suet might include peanut butter, peanuts, birdseed and cracked corn. The cage allows small birds and mammals to pick the suet cake apart without carrying the entire brick away.
A suet feeder is a great inexpensive way to keep woodpeckers and other potential pests from damaging your property. They can be purchased at most home improvement stores and online.