I am not a business expert and I don't have any economics background so bear with me on this one. Let's say you have an idea for a new business or product and before start building it, you'd want to validate it. How would you do that? How would you know that the idea might fly? How would you research the market to see if it would fit?

I apologize if my questions are vague, I don't know what would the starting points for this topic be.

Thanks!