What is a common ingredient in conditioners that helps to restore moisture?

Glycerin is a common ingredient in conditioners known for its ability to restore moisture to the hair. As a humectant, glycerin attracts water from the environment or from deeper layers of the hair, helping to keep the hair hydrated and preventing dryness. This moisture retention is essential for maintaining the overall health and appearance of hair, making it more manageable and less prone to damage.

In contrast, while silicone can provide a protective coating that gives hair shine and reduces frizz, it does not necessarily add moisture. Petrolatum and mineral oil are occlusive agents that create a barrier on the hair to trap moisture, but they do not actively attract or restore moisture the way glycerin does. Therefore, glycerin is the most effective ingredient listed for directly restoring moisture in conditioners.