Which hair product is used to define curls?

Curl cream or gel is specifically designed to enhance and define curls, making it the optimal choice for this purpose. These products typically contain ingredients that provide hold, moisture, and sometimes frizz control, allowing the hair to maintain its natural curl pattern without feeling stiff or crunchy.

Hair mousse, while it can add volume and some texture, does not specifically target curl definition in the same way. Leave-in conditioner primarily focuses on moisture and can help with overall hair health, but does not offer the level of hold required to define curls. Hair spray is generally used for setting styles and providing hold, but it is not intended for defining curls from the start, and may even weigh down or make them less bouncy if not used correctly.

Therefore, the use of curl cream or gel is key for achieving defined curls, making it the most appropriate choice in this context.