What substances are known for absorbing moisture or promoting retention of moisture in the hair?

Humectants are substances specifically designed to attract and retain moisture. They have a unique ability to bind water molecules from the environment and hold them within the hair structure, thereby helping to keep hair hydrated. This moisture retention is crucial for maintaining healthy, manageable hair, as it prevents dryness and brittleness.

In contrast, emollients primarily work to soften and smooth the hair, creating a protective barrier that helps to lock in moisture but does not inherently attract it. Conditioners serve to improve the hair's texture, manageability, and shine; they can contain various ingredients, including humectants, but are not exclusively moisture-absorbing agents. Proteins play a different role by strengthening the hair and repairing damage but do not contribute significantly to moisture retention. Therefore, humectants are recognized as the key substances for absorbing or promoting the retention of moisture in hair care.