A carrier account in Carriyo holds the settings for a given account with your chosen carrier. The information in the carrier account varies depending upon the carrier and it usually includes infromation such as the account number, the API credentails (API key, username, password etc), the chosen service type etc.
If you are business that uses multiple carriers for shipping, then you will have multiple carrier account. For instance, if you have an account with DHL and UPS, you will create two carrier accounts in Carriyo for each of your carrier with all the mandatory settings necessary to book and track your shipments. You can also setup multiple carrier accounts in Carriyo for the same carrier if you have multiple accounts with them for different service types or different countries etc.