Oxford Languages defines a conditioner as "a substance...used to improve the condition of something". When it comes to our hair, there are several properties a conditioner help with:
According to the Minnesota School of Cosmetology hair conditioners, “can reduce the number of split ends and strengthen the hair follicles to prevent damage.” It acts by working on the surface of the hair by closing the cuticle and adding a barrier around the hair strand to lock in moisture and hydration. When the cuticle is open or disrupted, this can cause the hair to break easily.
An excellent article written on the Josh Rose Brooks website says “The hair is technically dead and…because hair is not a living tissue with regenerative ability, it cannot heal and repair.” Even more so, his article explains why damaged hair cannot really be repaired either.
Protecting the hair in the first place is like brushing your teeth or washing the face; it needs to be done continually otherwise fixing the damage is harder and sometimes too late.
Conditioners improve the appearance of the hair by making it shine and luscious. Some conditioners do a better job than others, but most work by closing the cuticle. When they're closed, they lie flush on the hair strand, and this makes the hair more reflective and hence, shine.
Usually we shampoo our hair first to remove the build up of products, grease and dirt. The benefit of having a freshly cleansed head comes at a cost. The shampoo also washes away our natural hair oil, sebum, and this is when conditioners step in. Conditioners replace the lost sebum to provide shine and lubrication to our hair which is why it's easier to manage through brushing and even finger combing.