When you're looking for information to support your research, you don't want to use just any information -- you want to use the highest quality information. The same would be true if you were trying to find a restaurant to eat at with your friends. You could Google restaurants in Scarborough, and you would get a lot of results, but if you wanted to know which restaurants were the best, you would go to Yelp & check out the reviews.
While there isn't Yelp for scholarly information, there is a complicated process called peer review. When a scholar submits an article for publication, it gets reviewed by an expert in their field who assesses whether the article is high quality research.
Most databases you search in will have an option to limit your results to just peer reviewed sources so you can help ensure you're looking at the highest quality information.
For more information about peer review, check out the Peer Review guide created by the University of Toronto.