Expense tracking is the practice of recording and monitoring every purchase or financial outflow to understand where your money is going. It is the foundation of any effective budget, providing the real data needed to make informed decisions about spending, saving, and adjustments. Tracking can be done manually with a spreadsheet, automatically through bank integrations in apps like Mint or YNAB, or by reviewing bank and credit card statements monthly. Because estimating expenses often leads to blind spots and inaccuracies, relying on real data is critical for achieving real results. Even just a few weeks of diligent analysis can yield surprising insights.