Vegemite is a thick, dark brown Australian food spread made from leftover brewers' yeast extract with various vegetable and spice additives. It was developed by Cyril Callister in Melbourne, Victoria, in 1922, and it was first sold in stores on 25 October 1923.

Yeast extracts consist of the cell contents of yeast without the cell walls; they are used as food additives or flavorings, or as nutrients for bacterial culture media. They are often used to create savory flavors and umami taste sensations and can be found in a large variety of packaged food including frozen meals, crackers, snack foods, gravy, stock and more. They are rich in B vitamins. Yeast extracts and fermented foods contain glutamic acid, an amino acid which adds an umami flavor. Glutamic acid is found in meat, cheese, fungi and vegetables—such as broccoli and tomatoes. A number of other substances found in yeast extract provide aromas, some meat-like, when allowed to react under heat.