I highly recommend reading beancount’s documentation on this, as what I have in this document does not draw from the same well of experience that beancount does:
The fundamental law of accounting is as follows:
All transactions must sum to zero.
From the above law, this next law follows:
All accounts must sum to zero.
We could also say it like so:
Each time money is moved, we must take it from one account and move it into another account.
Following this fundamental law, which is called the Accounting Equation, gives us a way to detect accounting errors.
augr finance, like beancount, does away with the concept of debits and credits and replaces it with conventional signs for account types.