Which common ingredient in cosmetics acts as an emulsifier?

Lanolin is a natural emulsifier commonly found in cosmetics and skincare products. It is derived from the wool of sheep and serves to combine water and oil, which do not naturally mix. By stabilizing these mixtures, lanolin helps prevent the separation of oil and water, creating a smoother texture and more consistent product. This property makes it particularly useful in creams, lotions, and other formulations where a stable emulsion is desired.

In contrast, aloe vera primarily acts as a hydrating and soothing agent, providing moisture and relief to the skin without the emulsifying properties. Glycerin is also primarily a humectant, meaning it draws moisture into the skin rather than stabilizing emulsions. Cleansing milk, while it may contain emulsifiers, is more a product type that can be formulated with various ingredients, and it's not an ingredient itself. Hence, lanolin stands out as the key emulsifier in this context.