The marshmallow is a confection that, in its modern form, typically consists of sugar or corn syrup, water, gelatin that has been pre-softened in hot water, dextrose, and flavorings, whipped to a spongy consistency. The traditional recipe used an extract from the mucilaginous root of the marshmallow plant, a shrubby herb (Althaea officinalis), instead of gelatin; the mucilage was used to soothe sore throats.

Commercial marshmallows are a late-nineteenth-century innovation. Since Doumak's patented extrusion process of 1948, marshmallows are extruded as soft cylinders, cut in sections and rolled in a mix of finely powdered cornstarch and confectioner's sugar (icing sugar). Not all brands coat their marshmallows in confectioner's sugar. Most of the current brands of commercially available marshmallows, in the US and Canada, are made and copacked by Kraft Foods and Doumak, Inc, under such names as Jet-Puffed, Campfire, Kidd and numerous "private label" store brands.

Marshmallows are also used in hot chocolate or café mocha (mochachino), Mallomars, Peeps and other candy, Rice Krispie treats, ice cream flavors such as Rocky Road, and S'mores, on top of candied yams during Thanksgiving, and in several other foodstuffs. Americans eat about 90 million pounds of marshmallows a year.