Concepts Explained

The concepts and models behind the tools — explained simply and practically.

Browse concepts and open the full explanation.

A practical way to separate essentials from nice-to-haves so your spending matches your priorities.

A simple model describing how consumption relates to income, and why aggregate demand can fluctuate.

Why a dollar today is worth more than a dollar tomorrow, and how that affects saving, investing, and risk.

Income you earn by doing the work (time for money): why it matters, and how most people use it.

Income that can keep coming with limited ongoing effort: common sources, trade-offs, and what people typically do.