To put it briefly, an agency account is a kind of account that enables advertisers/affiliates to build and oversee several campaigns simultaneously. Owners of agency accounts can establish, manage, and alter the access rights of numerous subaccounts.

Using an agency account is incredibly advantageous for agencies and their clients. With just one platform, agencies can manage their clients' campaigns and optimize their operations. Time is saved, and there is a lower chance of mistakes. It gives clients a consolidated view of all campaigns, which facilitates performance tracking and helps them decide on advertising tactics.
Because using an agency account does not result in significant losses and allows for reimbursement requests even if the account is blocked, so many advertisers who run black hat offers prefer using them.