Final answer:
A customer database is the entity that holds demographic info, financial info, and billing.
Step-by-step explanation:
The entity that holds demographic info, financial info, and billing is a customer database. A customer database is a system that stores and manages information about customers, including their demographic data (such as age, gender, and address), financial data (such as payment details and transaction history), and billing information (such as invoices and payment records).
A customer database is commonly used by businesses to keep track of their customers and provide personalized services. It can be stored on a computer server or in the cloud and is accessed and updated by authorized personnel.