Thank you for the opportunity to help you with your question!
Promotion refers to raising customer awareness of a product or brand, generating sales, and creating brand loyalty. It is one of the four basic elements of the market mix, which includes the four P's: price, product, promotion, and place.
So customer promotion actually is an attempt to get the channels of distribution to stock more of a product.
I hope this would help you,but if you have any doubt regarding this,you can surely ask.