Landing pages allow you to create single pages (very minimal or no navigation links) that address the exact information a potential customer is looking for. Ideally each advertisement should point to a unique landing pages.
Additionally you can create A/B split tests of each landing page with the click of a button and automatically track how small changes affect your conversions.
Having the ability to quickly implement changes and new landing pages to address your ever changing marketing requirements for only $9 per page and $3 per A/B test will have a large effect on your businesses bottom line and ROI.
Landing pages are an extension of your full website and typically setup to appear on a subdomain like this: page.yourwebsite.com