White hat versus black hat

SEO techniques are classified by some into two broad categories: techniques that search engines recommend as part of good design and those techniques that search engines do not approve of and attempt to minimize the effect of, referred to as spamdexing. Some industry commentators classify these methods, and the practitioners who employ them, as either white hat SEO, or black hat SEO. White hats tend to produce results that last a long time, whereas black hats anticipate that their sites may eventually be banned either temporarily or permanently once the search engines discover what they are doing.

An SEO technique is considered white hat if it conforms to the search engines' guidelines and involves no deception. As the search engine guidelines are not written as a series of rules or commandments, this is an important distinction to note. White hat SEO is not just about following guidelines, but is about ensuring that the content a search engine indexes and subsequently ranks is the same content a user will see.

Webmasters and search engines

By 1997 search engines recognized that some webmasters were making efforts to rank well intheir search engines, and even manipulating the page rankings in search results. Early search engines, such as Infoseek, adjusted their algorithms to prevent webmasters from manipulating rankings by stuffing pages with excessive or irrelevant keywords.

Due to the high marketing value of targeted search results, there is potential for an adversarial relationship between search engines and SEOs. In 2005, an annual conference, AIRWeb, Adversarial Information Retrieval on the Web, was created to discuss and minimize thedamaging effects of aggressive web content providers.

SEO companies that employ overly aggressive techniques can get their client websites banned from the search results. In 2005, the Wall Street Journal profiled a company, Traffic Power, that allegedly used high-risk techniques and failed to disclose those risks to its clients. Wired magazine reported that the same company sued blogger Aaron Wall for writing about the ban. Google's Matt Cutts later confirmed that Google did in fact ban Traffic Power and some of its clients.

Some search engines have also reached out to the SEO industry, and are frequent sponsors and guests at SEO conferences and seminars. In fact, with the advent of paid inclusion, some search engines now have a vested interest in the health of the optimization community. Major search engines provide information and guidelines to help with site optimization. Google has a Sitemaps program to help webmasters learn if Google is having any problems indexing their website and also provides data on Google traffic to the website.Yahoo! Site Explorer provides a way for webmasters to submit URLs, determine how many pages are in the Yahoo!index and view link
information.

Getting indexed

The leading search engines, Google, Yahoo! and Microsoft, use crawlers tofind pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. Some search engines, notably Yahoo!, operate a paid submission service that guarantee crawling for either a set fee or cost per click. Such programs usually guarantee inclusion in the database, but do not guarantee specific ranking within the search results. Yahoo's paid inclusion program has drawn criticism from advertisers and competitors. Two major directories, the Yahoo Directory and the Open Directory Project both require manual submission and human editorial review. Google offers Google Sitemaps,for which an XML type feed can be created and submitted for free to ensure that all pages are found, especially pages that aren't discoverable by automatically following links.

Search engine crawlers may look at a number of different factors when crawling a site. Not every page is indexed by the search engines. Distance of pages from the root directory of a site may also be a factor in whether or not pages get crawled.