D-Biotin is the active form of vitamin B7. Most supplements already use this form, and absorption is the same across forms.
Many people take it for hair, skin, and nails. Evidence for these uses remains limited.
Biotin participates in energy metabolism, but targeted supplementation for that purpose is not standard.
As a water-soluble vitamin, you can take it with or without food. Dose recommendations vary widely, from small amounts up to 5,000 mcg and beyond. High doses can interfere with certain lab tests, so tell your healthcare provider you are taking it.