FUD stands for Fear, Uncertainty and Doubt.  FUD can grow your business and FUD can kill your business.

Grow 

If you can uncover a customer’s fear and then explain how your product or service alleviates that fear, you will make a sale.

If a customer is uncertain about something, you can educate them with content or your through your salesperson. This increases your odds of making a sale now or later.

If a customer has doubts about your solution, you can address then and make a sale. But only if you ask questions that can uncover those doubts.

Die 

If a customer fears that your company can’t deliver on its promises, you will lose the sale.

If a customer has uncertainty about the features of your offering (and how it will help her), you will likely lose the sale or, at best, extend the sales cycle.

If a customer doubts that you are a reputable firm, you will likely not get the sale.