Double entry bookkeeping involves making at least two equal entries for every transaction, with one entry recording a debit to one account and one recording a credit to another related account. Accounts represent a T-shaped balance sheet with debit and credit sides. For example, when reimbursing a collaborator's expenses, the credit entry is recorded in the bank account to show money decreasing, while the debit entry is recorded in the collaborator's account to show money increasing. Bookkeeping software like Bkper performs double entries for all transactions to keep debits and credits in balance.