"How to use rosemary oil for hair" is an infinitive phrase, a type of verb phrase that functions as a noun. It refers to the process of applying rosemary oil to the hair for various purposes, such as promoting hair growth, reducing dandruff, and improving hair health.
Rosemary oil, extracted from the rosemary plant, is known for its medicinal properties and has been used for centuries in hair care practices. It is rich in antioxidants and anti-inflammatory compounds, making it beneficial for scalp health and hair growth.