What are major concepts to be considered when closing a deal?

In my point of view closing a deal is a recap of your sales presentation where you can notice some buying signals and trying to obtain a YES from the customer to start business with your company.My major concept when closing a deal is to ensure that the customer fully understood the product/service/value that i'm offering and how that would effect him/her.Closing a deal is a start of a business relationship between a customer and a particular company or organization.