A gateway page is a page which is designed to attract the attention of search engines and potential users by quickly outlining the purpose and function of a website and providing people with an index of resources. Historically, gateway pages were regarded as very important for search engine optimization (SEO) and many websites used them. However, spammers have taken over the technique so effectively that some gateways can actually decrease search rankings because search engines may read them as spam and delist a website or lower its rank.
The idea behind a gateway page is that it should be simple, fast loading, and easy to navigate. It contains basic key information about the website, ideally stated with several keywords and variations upon those keywords so that a search engine will pick it up. A gateway page for a florist, for example, would be sure to include terms like "online florist," "floral delivery," "florist," "florists," "fresh flowers," and so forth so that people searching for these terms would be more likely to land on the gateway page.
Some sites may use several gateway pages which are designed to provide information about various areas of the site. A pharmaceutical company, for example, might have separate gateways for physicians and patients, and another gateway for job seekers interested in working for the company. Each gateway is tailored to the target audience with specific keywords and key phrases which are designed to make search engines see the site as relevant.
The practice of spamdexing has undermined the effectiveness of the gateway page. Aside from being useful for websites who wanted to attract traffic, gateway pages were often useful for site visitors who liked having a quick resource to use when looking up material on a website. Websites which continue to use such pages must structure them carefully so that it is clear that the page is not spam, and neither is the website attached to it. People generally think carefully about the percentage of content when compared to links and keywords to strike a balance which is high enough for a search engine to find the page, but not so high that it looks suspicious.
It can be difficult to get information directly from search engines about the thresholds they use when determining whether a site is a spam site or not, because the search engine does not want to provide spammers with a checklist of things to avoid doing. However, web designers who specialize in search engine optimization can assist people with structuring a website which will be attractive to search engines without looking like spam.