The lentil is an edible legume. It is a bushy annual plant known for its lens-shaped seeds. It is about 40 cm (16 in) tall, and the seeds grow in pods, usually with two seeds in each.

In South Asian cuisine, split lentils (often with their hulls removed) are known as dal. Usually eaten with rice or rotis, the lentil is a dietary staple throughout regions of India, Sri Lanka, Pakistan, Bangladesh and Nepal. As a food crop, the majority of world production comes from Canada, India and Australia.

Lentils are consumed in many ways. They can be eaten soaked, germinated, cooked, fried and baked. The most common preparation method is cooking. The seeds require a cooking time of 10 to 40 minutes, depending on the variety; shorter for small varieties with the husk removed, such as the common red lentil. Most varieties have a distinctive, earthy flavor. Lentils with husks remain whole with moderate cooking; lentils without husks tend to disintegrate into a thick purée, which leads to quite different dishes. The composition of lentils leads to a high emulsifying capacity which can be even increased by dough fermentation in bread making.

According to the USDA National Nutrient Database, 100 g of raw lentils (variety unspecified) provide 353 calories; the same weight of cooked lentils provides 116 calories. Raw lentils are 8% water, 63% carbohydrates including 11% dietary fiber, 25% protein, and 1% fat (table). Lentils are a rich source (20% or more of the Daily Value, DV) of numerous essential nutrients, including folate (120% DV), thiamin (76% DV), pantothenic acid (43% DV), vitamin B6 (42% DV), phosphorus (40% DV), iron (50% DV), and zinc (35%), among others (table). When lentils are cooked by boiling, protein content declines to 9% of total composition, and B vitamins and minerals decrease due to the overall water content increasing (protein itself is not lost). Lentils have the second-highest ratio of protein per calorie of any legume, after soybeans. Lentils contain the carotenoids, lutein and zeaxanthin, and polyunsaturated fatty acids.