Have I used commas correctly?Watch
Many businesses have many business ideas, and this is where market research comes in. Market research enables businesses to understand the trends of today, and for different existing markets. Although many tends go out of fashion eventually, their is still a minority of people who still love past trends and this is why business continue to sell some products for longer. If businesses intended to aim a new product at teenagers, then they would have to observe the younger market.
Your use of commas is okay, I guess... However, could be improved if you use a semicolon between the past trends comment and the 'this is why....'