To design a product according to the specific instructions of a customer. 

To design products according to the requirements of your customers.

(” I customized my interior of my car according to the way I wanted it, that is the reason why you can not find it any way else”).

To customize; to listen to the customers needs, comments, opinions and requests for the sake of upgrading, redesigning and reconstructing products that meets the needs of the customers.

In Today’s business; business companies do a lot of research and investigations via Facebook, blogs posted on the Internet, YouTube etc, so that they can be able to find out the people’s interests- Which helps them to customize their products that they sell. 

— cus·tom·iz·able adjective — cus·tom·i·za·tion noun — cus·tom·iz·er noun..


See also the meaning of a sustainable business.