Landing Page is a web page that appears when a visitor clicks on a PPC ad or a search engine result link. The home page of a website is not the only landing page; every page in a website has a purpose and is a potential search engine landing page. A landing page should contain content that relates to the keyword search phrase. For example, searching in Google for website mockup should bring up web landing pages that contain content relating to the keyword phrase "website mockup".
Website landing pages can be used for a couple different purposes, pay per click/marketing campaigns and search engine optimization. Using landing pages for pay per click and marketing campaigns can help determine a campaign's effectiveness. If you are advertising in materials off of the internet by appending a URL you are directing visitors to a page that is created specifically for that advertisement which can allow you to easily measure its effectiveness.
Search engine optimized websites often contain many landing pages. The more content a website has the higher its chances are to show up in the search engines. More landing pages also means more keyword phrase avenues a website can be found under. Landing pages are a great way to increase the number of site visitors and your search engine ranking.