A T-account is a visual tool used in accounting to represent individual ledger accounts. It looks like the letter "T", with the account name at the top. The left side is the debit side, and the right is the credit side. It's used to record and analyze transactions, helping accountants track how each affects different accounts (e.g., assets, liabilities, revenue). T-accounts simplify the double-entry bookkeeping process and help ensure accuracy in financial records.