Final answer:
Hunt's Merchant's Magazine and Commercial Review, launched in 1888, was vital for businesses to learn about advertising and to stay informed on trade and finance, heralding the era of modern advertising practices.
Step-by-step explanation:
The publication launched in 1888 that informed businesses why they should advertise and how to do it was Hunt's Merchant's Magazine and Commercial Review.
This monthly business review catered to the business elite by providing information on trade and finance, commodity prices, new laws affecting business, and statistics regarding imports and exports.
With competition increasing and the consumer market growing due to the wide variety of goods, advertising became a significant factor for businesses.
During this time, professional advertising agencies began to emerge and magazines started to serve as a platform connecting advertisers with consumers through vibrant print advertisements.