Money & Financial Concepts — Primer

TL;DR
Clear, compact definitions and practical examples of the foundational financial concepts: money, value, liquidity, inflation, real vs nominal returns, and time value of money (PV / FV). These concepts are the baseline for budgets, savings, investing, and borrowing.

1. What is money?

Definition: Money is any widely accepted medium of exchange, unit of account, and store of value used to facilitate trade.
Three functions:

1. Medium of exchange — accepted for buying goods and services.
2. Unit of account — a common measure for pricing.
3. Store of value — retains purchasing power over time (subject to inflation).

Notes: Forms of money include physical cash, checking deposits, and near-cash instruments (e.g., certain bank accounts). Cryptocurrencies and barter-like credits may serve some functions but vary in acceptance and stability.

2. Liquidity and types of assets

Liquidity: how quickly and easily an asset converts to cash without material loss of value.

• Most liquid: cash and checking accounts.
• Moderately liquid: savings accounts, money market funds.
• Illiquid: real estate, collectibles, private equity.

Why it matters: Liquidity planning determines where to hold emergency funds and how much to keep accessible.

3. Inflation and purchasing power

Definition: Inflation is a general, sustained increase in the price level of goods and services in an economy, measured as a percentage change (e.g., Consumer Price Index).
Effect: Inflation reduces purchasing power — the same nominal amount buys less over time.

Practical rule: Compare nominal returns to inflation to get the real return:
Real return ≈ Nominal return − Inflation rate

4. Real vs nominal returns

• Nominal return: stated percentage change in value (not adjusted for inflation).
• Real return: nominal return adjusted for inflation; shows true purchasing-power gain.

Example: A 5% nominal return with 2% inflation → ~3% real return. Use real return when planning long-term goals.

5. Time Value of Money (TVM)

Principle: A dollar today is worth more than a dollar tomorrow because of earning potential (interest, investment returns).

Key formulas:

• Future Value (FV): FV = PV × (1 + r)^n
• Present Value (PV): PV = FV / (1 + r)^n
  Where PV = present amount, FV = future amount, r = periodic interest rate (decimal), n = number of periods.

Use cases: Evaluating savings goals, comparing loan offers, valuing investments.

6. Common financial measures and terms

• APY (Annual Percentage Yield): annual growth rate including compounding.
• APR (Annual Percentage Rate): yearly cost of borrowing excluding compounding (may include fees).
• Yield: income return on an investment (dividends/interest).
• Principal vs Interest: original amount loaned vs cost to borrow.

7. How to use these concepts (practical steps)

1. Always compare returns after inflation (use real return).
2. For short-term goals and emergencies, prioritize liquidity over yield.
3. Use PV/FV when comparing cash flows across time (e.g., lump-sum vs payment plan).
4. Use APY for deposit-product comparisons and APR for loan comparisons.

8. Tools & Calculators

• PV / FV calculator (embed): estimate how much to save now for a future goal.
• Inflation-adjusted return calculator: translate nominal returns to real returns.

FAQ

Q: What is the simplest definition of inflation?
A: Inflation is a sustained increase in the general price level, reducing the purchasing power of money.

Q: When should I use PV vs FV?
A: Use PV to determine what future money is worth today (e.g., lump-sum loan offers). Use FV to project current savings forward (e.g., retirement balance projection).

Q: Is APY or APR better for comparing accounts and loans?
A: Use APY to compare deposit products (reflects compounding). Use APR to compare loan costs (includes fees but not compounding).