No expert at all. I am just lucky to have one of my sisters and one of my sister-in-laws who are excellent cooks.
Kaffir lime (in Thai, we call it Ma-grood). For a culinary purpose, only leaves and rind is used, not the juice (very unlike limes or lemons). Kaffir lime rind is one of key ingredients of many kinds of curry paste in Thai cuisine.
However, juice, rind and leaves are used for medicinal purposes.
Growing up, we used magrood juice as hair cleanser. It is supposed to keep your hair clean, healthy and shiny. After you shampoo your hair and rinse it off, wet your hair thoroughly with magrood juice. Wait 10 minutes before rinsing it off. Your hair will be clean and shiny. Magrood juice is supposed to clean off chemicals you put on your hair and restore your hairās quality.