Hair fetish involves sexual arousal related to hair - long hair, specific hair types, hair styling, braiding, or the act of touch/pulling. Some focus on head hair, others on body hair.
For some, long flowing hair is inherently arousing. Others enjoy the sensation and control elements of hair play - pulling, braiding, binding. Some combine it with power exchange.
The appeal can be aesthetic, tactile, or psychological. Hair can signal youth, femininity, strength, or other qualities that trigger arousal.
Safety generally involves consent for pulling intensity, being gentle enough to avoid damage, and hygiene if involving saliva or fluids.