Where the words come from
Recession, depression, peak and trough defined, the business cycle as movement from peak to trough and trough to peak, and unemployment as a lagging indicator of business activity — Principles of Economics 2e, OpenStax, licensed CC BY 4.0. https://openstax.org/books/principles-economics-2e/pages/19-3-tracking-real-gdp-over-time and https://openstax.org/books/principles-economics-2e/pages/21-introduction-to-unemployment. Changes: "We call the highest point of the economy, before the recession begins, the peak" and "the lowest point of a recession, before a recovery begins, is the trough" recast as card definitions; the US NBER record and Table 19.7 dropped; 2008 recession timing kept from the Chapter 21 introduction; the boom card, the UK two-quarter convention, the chart and the labels Y1 to Y3 and t1 to t3 are ours; British spelling.
Inflation during and after booms and falling in recessions, unemployment higher in recessions and lagging upswings, tax receipts and benefit spending moving with the cycle, and strong growth widening a trade deficit — Principles of Economics 2e, OpenStax, licensed CC BY 4.0. https://openstax.org/books/principles-economics-2e/pages/24-5-how-the-ad-as-model-incorporates-growth-unemployment-and-inflation and https://openstax.org/books/principles-economics-2e/pages/30-5-automatic-stabilizers and https://openstax.org/books/principles-economics-2e/pages/23-4-the-national-saving-and-investment-identity. Changes: Condensed from 24.5, 21.2 ("unemployment tends to lag changes in economic activity"), 30.5 and 23.4 ("a period of strong economic growth tends to make a trade deficit larger"); US figures dropped; British spelling.
The question and the page layout are our own.