Hair conditioner covers the hair with a thin coating of either grease or a plastic-like substance.
You may be wondering why people would do this just after using a shampoo to strip the oil out of their hair.
There’s a good reason: Hair is very jagged. Under a microscope, you can see notches all up and down the shaft.
After we wash our hair, taking all the oils out, rough spots catch on each other and hairs stick together, forming tangles and making hair more susceptible to splitting and breaking.
When conditioner is applied, it fills in these rough spots with a lubricating substance, smoothing out the hair strand.
As a result, hair feels nicer, lies flatter, and is easier to brush and comb.