In the 1960's, E Jerome McCarthy came up with the 4 Ps of marketing: product, price, place, promotion. Essentially, these 4 Ps explain how marketing interacts with each stage of the business.
Product
Let's say you come up with an idea for a product you want your business to sell. What's next? You probably won't be successful if you just start selling it. Instead, you need your marketing team to do market research and answer some critical questions: Who's your target audience? Is there market fit for this product? What messaging will increase product sales, and on which platforms? How should your product developers modify the product to increase likelihood of success? What do focus groups think of the product, and what questions or hesitations do they have?
Marketers use the answers to these questions to help businesses understand the demand for the product and increase product quality by mentioning concerns stemming from focus group or survey participants.