Agar is used as an alternative to gelatin primarily to accommodate dietary restrictions such as vegetarianism or veganism; because gelatin is derived from bones and other animal-derived products, it is not a suitable ingredient for those who do not eat animal products. As a suitable ingredient for vegetarian or vegan diets, agar is a plant-derived thickening or solidifying agent.
Agar is derived from seaweed and is processed into flavorless fakes, powders or bars. Agar can also be known as "agar-agar" or "kanten." Although agar is used as a substitute for gelatin, it is not an exact equivalent, as it typically turns out more solidly and less jiggly than gelatin. However, agar can be thinned out and used in lower proportions to create a thickening rather than a solidifying effect. Those who end up with agar that is not powdered should break off parts of the bar, or take a designated amount of flakes and grind these alternatives into a powder to ease dissolution. One benefit of agar is that it can set at room temperature and doesn't require refrigeration as some gelatin recipes do. Agar takes about an hour to set, and can be melted down and reused if a recipe is botched.