A billing address is the address connected to a specific credit or debit card. Companies use it to verify authorized use of such a card. It is also where companies send paper bills and bank statements.
Billing addresses must match what the credit card company has on file, or the attempted purchase won't go through. When the cardholder moves, the billing address must change to match the holder's current address. This can be accomplished by contacting the credit card company.
The billing address is different from the shipping address, which is the address where packages get delivered. Billing and shipping addresses may be the same, but are sometimes different.