Aachar (आचार) means conduct or code of conduct. In Jainism it refers to the proper ethical and behavioral rules that guide a Jain’s daily life and spiritual practice.

• Core idea: living in a disciplined, virtuous way to progress on the path to liberation.
• Right conduct (Samyak Achar) is central to Jain practice and complements right faith (Samyak Darshan) and right knowledge (Samyak Jnana).
• For lay practitioners, Aachar is expressed through the five main vows (mahavrat) and/or the five life-values (anuvratas): non-violence (ahimsa), truth (satya), non-stealing (asteya), celibacy or sexual restraint (brahmacharya/partially practiced for laypeople), and non-attachment to possessions (aparigraha).
• For Jain monks and nuns, Aachar is even more strict and detailed, with a codified set of rules governing conduct, diet, dress, and activities. There are small differences in practice between Digambar and Shwetambar traditions, but both emphasize non-violence, truth, restraint, and humility.

If you’d like, I can provide the specific wording of a traditional Aachar verse or describe how Aachar is applied in daily life for laypeople versus ascetics.