How fast is the economy growing? Is it speeding up or slowing down? How does the trade deficit affect economic growth? What's happening to the pattern of spending on goods and services in the economy? To answer these types of questions about the economy, economists and policymakers turn to the national income and product accounts (NIPAs) produced by the Bureau of Economic Analysis (BEA). Included in the NIPAs is gross domestic product (GDP), which measures the value of the goods and services produced by the U.S. economy in a given time period. This book is intended as an introduction to the GDP and NIPAs for the new user. It considers the transactions that occur in a simple economy in order to introduce such economic concepts that underlie the NIPA's. It describes the NIPA sectors for which economic activity is measured and the use of T-accounts to illustrate economic flows. An overview of the derivation of the NIPA measures are also given, including inflation-adjusted, or "real" estimates. In addition, references, organised by subject area are provided, for users interested in moving beyond an introduction to a more in-depth or advanced information about economic accounting and the NIPAs.