There are two major types of conditioners, no penetrating and penetration. The non-penetration conditioner coats the cuticle layer of the hair with a microfilm coating.
The penetrating conditioner goes deep into the cortex layer of the hair shaft to restore vital proteins. Both can be used at the same time, and they should be.
High quality conditioners, when used regularly, will reduce cuticle roughness and help the hair be stronger, shine, and feel better. The conditioner will leave a microfilm coating on the hair, and counteract static electricity so that the hair will be more manageable.
Remember ladies to try to condition the hair at least 2-3 times a week when first beginning your regimen. It helps to make the hair stronger so that it can with stand the elements.