Its goal is to keep the attention of the client and induce them to make a purchase. The average of this landing page is + 10% to traffic conversion for your site.
The secret is in the minimum amount of information and its urgency. Landing describes not the goods, but the benefits that a person will receive after acquiring it. Only specific information, concise design and loud calls for action.
Each element of Landing works for you: headers, information blocks, design - all this is aimed at selling your product or service. There're no distractions (advertising, links to other products, etc.). It allows you to concentrate the buyer's attention on one element, which at times increases his interest in making a purchase.