Snehana (or Sneha) is a general term for a range of Ayurvedic Oleation therapies, which can be done both internally (Abhyantara Snehana) and externally (Bahya Snehana). Snehanas can be applied stand-alone, but they are also important Ayurvedic therapies to prepare the body to receive specialized Panchakarma treatments.
Snehana is applied with a variety of medicated oils, fats, ghee, and herbs with the goal of detoxifying organs, and nourishing, lubricating and softening body tissues and skin. The type of oils and herbs used depend on the specific aim of the treatment and which Doshas need to be treated.
Internal Snehana is applied orally, through the nose (Nasya), or as an enema. External Snehana can be anything that includes the application of oil on the body surface in combination with a head, foot or full body massage, and such.
In fact, External Snehana is often named in one go with Abhyanga Massage, which is Snehana Oleation therapy including a full body massage.