Dal is a pulse or lentil that grows in pods. Whole dal are the lentils that are removed from their pods, dried, and sold whole, whereas split dal is split into thinner flatter discs. Whole dal can either have its skin on or off (shelled vs. non-shelled) whereas split dal is more commonly hulled.
Lentils are classified as grain legumes, also known as pulses. This means that the part we eat is the seed, which is high in fiber and protein.
Generally used to prepare maa ki dal or dal makhani, urad dal is one of the richest sources of protein and vitamin B. Low in fat and calorie, urad dal is also rich in iron, folic acid, calcium, magnesium and potassium.