In HTML authoring, there are very good reasons to include an alt attribute into every IMG element. The purpose is to specify a textual replacement for the image, to be displayed or otherwise used in place of the image. Thus, the prime rule is: Consider what the page looks like or sounds like when images are not shown. Then, write for each image an alt text that best works as a replacement. " Detailed see http://www.cs.tut.fi/~jkorpela/html/alt.html.

A popular search engine with the largest database on the web, indexing more than 140 million pages. Its main URL is http://www.altavista.com. Until 1998, this search engine provided the search facility for Yahoo. Altavista indexes all the words in a web page, and new pages are normally added to the database fairly quickly, within a couple of working days. You are asked to submit just the main page of your site. The Altavista spider will then explore your site and index a representative sample of the pages. Some problems with spamming have been noticed. The use of keyword Meta tags is penalized. Altavista places various alternative options before its search results, including suggested questions (using the Ask Jeeves service), RealNames. Paid entries are beginning to appear at the start of the search results.

The default search engine for users of the AOL internet service provider, and hence a busy site. Its URL is http://www.netfind.com. It is essentially the same engine as Excite.

A Meta search engine which can be asked questions in English. This service is also in use at Altavista. http://www.askjeeves.com.

A Banner advertising is a set of images that are identical in size and shape (a rectangular image). It functions like a billboard and is displayed on a web site. Visitors can click on these banners and be transported to your web site immediately.

A search allowing the inclusion or exclusion of documents containing certain words through the use of operators such as AND, NOT and OR.

Lists of links to selected (and usually popular) web sites. The links are maintained by search engines and directories and are sorted into categories or channels. Sites are picked by a channel editor, often because of a site's already high ranking with the search engines. Some search engines and directories allow visitors to nominate sites for inclusion in their channels.

The process of clicking on a link in a search engine output page to visit an indexed site.
This is an important link in the process of receiving visitors to a site via search engines. Good ranking may be useless if visitors do not click on the link which leads to the indexed site. The secret here is to provide a good descriptive title and an accurate and interesting description.

The hiding of page content. Normally carried out to stop page thieves stealing optimized pages.

The listing of only one page from each website in a search engine or directory's list of search results. This avoids occupation of all the top results by a small number of web sites and makes the list of results clearer and more useful to the user.

The HTML <!-- and --> tags are used to hide text from browsers. Some search engines ignore text between these symbols but others index such text as if the comment tags were not there. Comments are often used to hide JavaScript code from non-compliant browsers, and sometimes (notably on Excite) to provide invisible keywords to some search engines.

A search for documents related conceptually to a word, rather than specifically containing the word itself.

That part of a search engine which surfs the web, storing the URLs and indexing the keywords and text of each page it finds.