Which ingredient is commonly used to create hold in hairstyling products?

Hairspray is specifically formulated to provide hold and maintain the desired shape and style of hair. It does this through ingredients that create a film over the hair strands, allowing them to stay in place even under various conditions. Hairspray can vary in hold strength, from light to extra-hold, catering to different hairstyling needs.

The other ingredients listed serve different purposes: water is essential in many formulations but does not provide hold; alcohol is often included for its quick-drying properties but can also dry out hair; and glycerin is primarily a humectant, attracting moisture but not contributing to hold in the same way as hairspray. Thus, hairspray stands out as the go-to ingredient for creating and sustaining hold in hairstyling.