Paryushan is one of the most important festivals in Jainism, devoted to introspection, spiritual upliftment, and penance. During Paryushan, Jains follow strict codes of conduct and avoid certain activities (known as "na krtavyo" or things not to be done) to maintain purity of mind, speech, and body.

Here are some of the main "na krtavyo" (do-nots) during Paryushan:

1. Violence (Himsa): Do not harm any living being, even unintentionally. Extra care is taken to avoid killing even the smallest life forms.
2. Eating After Sunset: Eating at night is strictly avoided. Many observe fasting or eat only once a day.
3. Root Vegetables: Do not consume root vegetables (like potatoes, onions, garlic) as their harvesting kills the entire plant and many microorganisms.
4. Unnecessary Movements: Avoid unnecessary travel or physical movement to minimize violence to living beings.
5. Entertainment: Refrain from entertainment or indulgence in sensory pleasures (such as watching TV, listening to music, etc.).
6. Falsehood (Asatya): Do not lie or speak harsh words.
7. Greed and Possessiveness: Avoid accumulation and excessive attachment to material possessions.
8. Anger and Ego: Do not indulge in anger, pride, deceit, or greed.
9. Luxury Food and Drinks: Avoid rich, elaborate, or luxury food items; keep meals simple and sattvic.
10. Criticizing Others: Do not criticize or speak ill of others; practice forgiveness.

The focus during Paryushan is on self-discipline, forgiveness, repentance (pratikraman), and spiritual purification. Following these "na krtavyo" helps in observing the true spirit of Paryushan according to Jain philosophy.