AI Tutor
If you spend $500 in cash to buy inventory, did your business just get poorer, richer, or stay the exact same?
The answer is that your total wealth did not change at all — you simply swapped one resource for another. This two-sided reality is the foundation of modern business accounting.

The Fundamental Equation

Every business owns valuable resources called assets (like cash, inventory, and vans), which are funded either by outside lenders as liabilities (like bank loans) or by the owner as equity (also called capital).
Because every single resource must come from one of these two sources, total assets must mathematically equal liabilities plus equity at all times: Assets=Liabilities+Equity\text{Assets} = \text{Liabilities} + \text{Equity}
How do we ensure this scale never tips over when business happens every day?

The Duality Concept

In 1494, Italian mathematician Luca Pacioli published the first formal system of double-entry bookkeeping to help Venetian merchants track trade without losing a single coin.
Pacioli codified the duality concept (or dual aspect concept), which states that every single economic transaction has two simultaneous, equal effects on the accounting equation.
Can a transaction change only one side of the equation, or must it always cross over?

Four Ways Transactions Balance