If your page (or site) has inbound links from sites in a search index, then Google (or any other broad search engine) will most likely find you pretty quickly. However, it’s peculiar but true: different search engines index different portions of the Web. Also, at any given time, it is impossible for any search engine index to include the entire Web!

To avoid being left out, it makes sense to manually add your URLs to search engines. (In early times there might be more of a delay before your sites were found, and it really made sense to make sure you were listed!)

To manually add your URL to Google, go to http://www.google.com/addurl/. You can get listed at Yahoo! at http://submit.search.yahoo.com/free/request.

Getting listed is, of course, only the beginning of the battle. One of the key goals of core SEO is to get both highly ranked and listed in reference to some specific search terms. Achieving this goal requires taking affirmative control of the information that the search index may use to make ranking decisions—and that it will use to understand the quality of your pages.

Taxonomies are categorized directories of information. A directory differs from the index used by a search engine because a directory uses a structured way to categorize sites. An often-used analogy is that a directory is like the table of contents in a book, while the search engine index is like the, well, index to the book. In other words, the directory tells you how the book is organized, while the index allows you to search within the book for specific keywords.

It’s a not-so-well-kept secret that one of the best approaches for getting good placements in the search engine listings is to enter through a back door, by working with the two most important structured directories: the Open Directory Project (ODP) and the Yahoo! Directory.

The Open Directory Project (ODP), http://dmoz.org, is the most important taxonomic directory on the Web. Formally hosted and administered by the Netscape division of AOL, the ODP is run along the lines of an open source project with the belief that “humans do it better.”

The ODP believes that web-automated search is ineffective, and getting worse, and that the small contingent of paid editors at commercial web search engine companies cannot keep up with the staggering rate of change on the Web—decaying stagnant sites, link rot, new sites, sites intended as search spam, and so on.

The ODP is run and maintained by a vast army of volunteer editors. These editors follow internal checks and balances to keep the integrity of the directory. See http://dmoz.org/guidelines/ for more information about the ODP review process and guidelines for site inclusion.

You, too, can become an ODP editor in an area of your interest and expertise. See http://dmoz.org/help/become.html for more information about becoming an ODP editor. This is a partially facetious suggestion, but one of the most effective ways to use SEO to promote your sites is to follow the patterns and practices of the ODP to get your sites included. You’ll find an FAQ about how to add your site at http://www.dmoz.org/add.html (this FAQ is also available via a link from the ODP home page).

The ODP taxonomy (categorization system) and the sites included in the categories are freely available as data for use by anyone who wants to run their own search engine as long as the terms of the ODP’s free-use license is complied with.

Google, and most of the major search engines, do use information derived from the ODP, but each major search engine uses it in their own way. With Google in particular, information from the ODP is used to form the Google Directory, http://directory.google.com.

Most significant, inclusion within an ODP category means that your site is very likely to be included within the Google Web index (as well as the Google Directory, and in other major web indices) as a high-ranking result for searches within that category.

So it’s worth submitting your site to the ODP, if only because it’s the best way to get indexed by search engines, including Google—and, to a significant extent, to manage how your site is categorized.

The Yahoo! Directory, a somewhat lesser known part of Yahoo!, works in pretty much the same way as the ODP, except that it is privately maintained Sites added to the Yahoo! Directory tend to end up in the Yahoo! index, as well as other important search indices, often with high ranking in response to searches related to the Yahoo! Directory category for the site.

To suggest your site for inclusion in the Yahoo! Directory, open the Yahoo! Directory’s home page, http://dir.yahoo.com/.

You can also find the Yahoo Directory by opening the main Yahoo! home page, selecting Directory as your search category, and searching for a term. The search results you will be presented with are from the Yahoo! Directory (not the Yahoo! Web index), and the display will show where in the taxonomy you are, so you can browse through related categories.

Wikis—and particularly the Wikipedia, found at http://www.wikipedia.org/—are community-based knowledge systems. The Wikipedia, and other select wikis, turn out to be excellent grist for the SEO link placement mill. Anyone can add content to a wiki, and the content tends to be authoritative. A link to your site strategically placed in a Wikipedia article may generate considerable traffic, and is likely to boost your sites standings with Google and other search engines.

The note of caution here is that placements should be relevant. Irrelevant spam links that don’t have anything to do with a topic in a wiki are likely to be deleted by the community quickly. In addition, SEO has grown up from the early days, and practitioners realize that what goes around comes around, and that spam is evil. In other words, craft wiki text and links with care and make it valuable content for the wiki—and, in doing so, better serve your SEO goals.