A landing page is a website page that shows up when a guest clicks on a PPC advertisement or a search engine result link. The home page of a website isn't the main landing page; each page in a website has a reason and is a potential search engine landing page. A landing page is a page on your site that is designed to convert visitors into leads. A landing page is unique in relation to different pages in that it pursues both of these criteria:
First, it has a shape that allows you to catch a visitors data in exchange for a desired offer. Second, the sole reason for the landing page is to convert visitors into leads (ie a homepage with a form on it doesn't consider a landing page since it fills different needs also). A landing page should contain content that identifies with the keyword search query. For example, searching in Google for website mockup should raise web landing pages that contain content identifying with the keyword phrase "website mockup".