According to Seth Godin, optimised specifically to encourage 1 of 5 actions:

1. Get a visitor to click (to go to another page, on your site or someone else’s)
2. Get a visitor to buy
3. Get a visitor to give permission for you to follow up (by email, phone, etc.). This includes registration of course.
4. Get a visitor to tell a friend
5. Get a visitor to learn something, which could even include posting a comment or giving you some sort of feedback

In online marketing a landing page, sometimes known as a lead capture page, is the page that appears when a potential customer clicks on an advertisement or a search-engine result link. The page will usually display content that is a logical extension of the advertisement or link, and that is optimized to feature specific keywords or phrases for indexing by search engines. In pay per click (PPC) campaigns, the landing page will also be customized to measure the effectiveness of different advertisements. By adding a parameter to the linking URL, marketers can measure advertisement effectiveness based on relative click-through rates.

Every page of a site indexed by search engines is a potential landing page.

The goal of search engine optimization (SEO) is to leave few landings to chance. The content of the page and/or links to the page are optimized for very specific, carefully researched keywords and phrases. Those keywords and phrases that are of most value for “organic” or “natural” search engine optimization are those most likely to be used by prospective customers in their search engines. Good choices will cause the site to rank higher in search engine results. For large websites covering many products or many topics, a single home page cannot be optimized for every topic and still be relevant to all. A different approach is needed, a landing page that will not convert a visitor directly. A “hub” page is optimized for more generic, less targeted keyword phrases that have naturally a lower conversion rate than more-specific search terms. Hub landing pages serve as a “mini portal” within a site – the site establishes a number of virtual home pages, each for a broader topic.