In Jainism, "Athanaak Tap" refers to the twenty types of austerities (Tapas) undertaken for spiritual purification and progress on the path of liberation (moksha). These austerities are divided into two categories: external (Bahirang Tap) and internal (Antarang Tap).

1. Six External Austerities (Bahirang Tap):

1. Anashana – Fasting (complete abstinence from food)
2. Avamodarya – Eating less than one's normal appetite
3. Vritti-sankshepa – Limiting the number of items or variety of food
4. Rasa-parityaga – Renunciation of tasty foods (spices, sweets, etc.)
5. Vivikta-shayyasan – Practicing solitude in sitting and resting places
6. Kaya-klesha – Physical endurance of discomfort (e.g., bearing cold, heat, etc.)

2. Six Internal Austerities (Antarang Tap):

1. Prayaschitta – Repentance or atonement for past wrongdoings
2. Vinaya – Humility and respect for elders, teachers, and monks
3. Vaiyavritya (Vaiyavritya) – Rendering service to ascetics and needy persons
4. Swadhyaya – Study of scriptures and self-study
5. Vyutsarga – Renunciation (particularly of attachment to body and possessions)
6. Dhyana – Meditation and contemplation

3. Eight Additional Austerities: Some Jain texts enumerate an additional eight forms of Tapas to make a total of twenty (20 Athanak Tap), often by further subdividing or elaborating on the above or including practices such as:

1. Uttam Kshama – Supreme forgiveness
2. Uttam Mardava – Supreme humility
3. Uttam Arjava – Supreme straightforwardness
4. Uttam Shaucha – Supreme contentment/purity
5. Uttam Satya – Supreme truthfulness
6. Uttam Sanyam – Supreme self-restraint
7. Uttam Tap – Supreme austerity
8. Uttam Tyag – Supreme renunciation

These last eight are also known as the eight fundamental virtues (Ashta Mula-guna) and are sometimes included in lists of 20 austerities.

Summary Table:

| External Tap (6) | Internal Tap (6) | Additional (8) | |-------------------|------------------|--------------------| | Anashana | Prayaschitta | Uttam Kshama | | Avamodarya | Vinaya | Uttam Mardava | | Vritti-sankshepa | Vaiyavritya | Uttam Arjava | | Rasa-parityaga | Swadhyaya | Uttam Shaucha | | Vivikta-shayyasan | Vyutsarga | Uttam Satya | | Kaya-klesha | Dhyana | Uttam Sanyam | | | | Uttam Tap | | | | Uttam Tyag |

These austerities are central to the Jain path of spiritual purification, helping to destroy karma and attain self-realization. Practicing these tap helps in controlling desires, purifying the soul, and progressing towards liberation.