A blender is a kitchen and laboratory appliance used to mix, puree, or emulsify food and other substances. A stationary blender consists of a blender jar with blade at the bottom, rotated by a motor in the base. The newer immersion blender configuration has a motor on top connected by a shaft to a blade at the bottom, which can be used with any container.

The blending container can be made of glass, plastic, stainless steel, or porcelain, and often has graduated markings for approximate measuring purposes. At the top of the container is a lid to prevent ingredients from escaping during operation. At the bottom is a blade assembly, sometimes removable for cleaning purposes. In cases where the blades are removable, the container should have an o-ring or gasket between the body of the container and the base to seal the container and prevent the contents from leaking. The blending container is generally shaped in a way that encourages material to circulate through the blades, rather than simply spinning around.

The container rests upon a base that contains a motor for turning the blade assembly and has controls on its surface. Most modern blenders offer a number of possible speeds. Low-powered blenders require some liquid to be added for the blender to operate correctly. This is because the liquid is used to move the solids around the jar and bring it in contact with the blade as the "whirlpool" fluid movement brings items from the top to the bottom. High-powered blenders are capable of milling grains and crushing ice without such assistance.

The hand-held immersion blender has no container of its own, but instead has a mixing head with rotating blades that can be immersed in a container. Immersion blenders are convenient for homogenizing volumes that are too large to fit in the bowl of a stationary blender or, as in the case of soups, are too hot to be safely poured into the bowl.

Some of the functions of blenders have been taken over by food processors. In particular, thicker mixtures such as mayonnaise and hummus are conveniently made in food processors.