Final answer:
The most important development in the history of advertising was the invention of graphic design, which allowed for the quick and affordable dissemination of information. The Industrial Revolution made advertising necessary, and television advertisements in the 20th century transformed the industry.
Step-by-step explanation:
The most important development in the history of advertising was the invention of graphic design. It had its beginnings in the 15th century with the invention of moveable type, which allowed for the quick and affordable dissemination of information. However, it was the Industrial Revolution in Europe and America that made advertising necessary. With the proliferation of products, businesses needed to reach a wide audience of potential buyers, and eye-catching graphic design became an essential part of advertising. The development of television in the 20th century also played a significant role in transforming the advertising industry. The first television advertisements were run in the early 1950s by presidential candidates Dwight D. Eisenhower and Adlai Stevenson. Advertisers began to use animation, jingles, and engaging content to capture viewers' attention.