Search engine marketing, like any other specialized field, is full of jargon. Below is a list of terms you should know if you manage a web site. Some of them, you may have already come across in your reading.

Algorithm  A complex mathematical equation used to determine a web site's rank.

Crawler  See spider.

Click through  The process of clicking on a link in search engine result pages to visit an indexed site. Good rankings mean nothing without click throughs. The secret here is to provide a good title and an accurate and interesting description.

Directory  These differ from search engines in that they are usually compiled manually by user submission, and often involve an editorial selection and categorization process. Yahoo, Open Directory, and Looksmart are all examples of directories.

Doorway Page  Also known in the search engine marketing business as bridge pages, entry pages, gateway pages, informational pages or portals, these are web pages that are specially designed to rank high in the search engines for particular keywords.

Index  1. The catalog of web pages maintained by a search engine or directory. 2. The default page or home page of a web site.

Keyword  The everyday words that people enter in search engines to find information, products and services. Keywords form part of a search engine query.

Keyword Frequency  The number of times a keyword appears in the text of a web page.

Keyword Density  How close together keywords appear in the text of a web page. Some search engines use keyword density to measure relevancy.

Keyword Prominence  How prominently keywords appear in the text of a web page. Title tags, headers, the beginning of paragraphs and hyperlinks, are just some of the places keywords should feature prominently.

Link Popularity  The number and quality of inbound links that a site has.

Meta Search Engine  A search engine which passes queries on to many other search engines and/or directories and then summarizes all the results. Examples include Metacrawler, Dogpile, and Mamma.com.

Pay Per Click Search Engine  A search engine where advertisers bid for placement.

Placement  Also called positioning or ranking by search engine marketing people, the process whereby a search engine places web sites in an order so that the most relevant sites appear first in the search results for a particular query.

Search Engine  Although the term is often used to describe both search engines and directories, the two are not the same. A search engine is a server or a collection of servers dedicated to indexing internet web pages, storing the results and returning lists of pages which match particular queries. The indexes are normally generated using spiders. Major search engines include: Google, Lycos, and Altavista.

Query  A word, a phrase, or a group of words used to pass instructions to a search engine or a directory in order to locate web sites.

Spamming  1. The use of redundant or unethical techniques to improve search engine placement and give irrelevant pages high search engine ranking. 2. To send unsolicited or unwanted messages.

Spider  The software that scans documents and adds them to an index by following links. Spider is often used as a synonym for search engine.

Relevancy  How well a web page provides the information a user is looking for, as measured by the user.

Traffic  The visitors to a web page or web site.