The advertising industry is a global, multibillion-dollar business that serves as a conduit between manufacturers and consumers. The research group eMarkerter reported that total media advertising spending globally was nearly $629 billion in 2018, with about 44 percent of that spending in digital advertising. There are more than 71,555 advertising businesses in the United States, employing more than 264,021 workers.

Whether for nonprofit organizations or Fortune 500 companies, advertising agencies are hired to cultivate brand identities, persuade consumers to switch brands, launch new products, and lobby for political issues. The advertising industry creates and manages the connection between companies, products, and consumers, translating their clients’ messages into effective campaigns. Advertising can stimulate buying, increase sales, and help to jumpstart the economy. The economy, though, can also affect the advertising business. When it slows down, consumers tighten their wallets, and manufacturers, in turn, reduce production and scale back on promotions. Ad spending decreases, as does ad revenue.

Popular media and technology drives this industry. Before the advent of radio, television, and computers, print publishing was the main method of advertising, with ads appearing in newspapers and magazines, flyers, and on billboards. Benjamin Franklin pioneered advertising tactics in his newspaper, the Pennsylvania Gazette, when he placed headlines, advertisements, and illustrations alongside editorial content. Franklin also owned a stationery store in Philadelphia and is believed to have been the first to create the mail-order catalog. Until the mid-1800s, little changed in how print advertisements looked. In newspapers, all print ads were usually a single column without special type or illustrations. Publishers weren’t in favor of advertisements and often separated them from the rest of the content. Magazine publishers, for instance, isolat...