The CBD stands for Central business services.
Even with modern technology, many professionals still exchange information through face-to-face contact. Business services, such as advertising, banking, finance, journalism and law, are centrally located to facilitate rapid communication of fast-breaking news
An example of a comsumer service is a store that sells clothing.
An example of a consumer services is a restaurant
An example of consumer services is a business that sells sporting goods
Consumer services in the CBD serve the many people who work in the center and shop during lunch or working hours. These business sell office supplies, computers, and clothing, or offer shoe repair, rapid photocopying, dry cleaning, and so on
The CBD of the USA is New York City
Singapore: A view of Central Business District
Central Business District Zoning - Stephanie Mercandetti