Algorithm - The complex set of rules that a search engine follows to determine the placement of a web page in the results pages of a search engine.

Alternate text, or Alt Text - The text that pops up when you put your mouse on top of an image or a picture.

Back Link - A link from one website to another.

Blind Link - A link that misleads the person viewing it. For example, an advertising banner may indicate that the person can answer a survey question, but clicking to answer the questions takes the user to a page of advertising.

Broken Link or Dead Link - A link that produces a 404 page not found error.

Cache – Pronounced like “cash,” cache is a snapshot of a web page for storage in a temporary storage area where the data can be stored for rapid access.

Cloaking – An underhanded technique in which one version of an optimized page is shown to the search engines and a different version of the same page is shown to the site’s human visitors. Most search engines will penalize a site if they discover cloaking.

Cross Link, or Reciprocal Link - Sites that exchange links with each other.

Deep Link - The act of linking to a page within a web site rather than linking to the main or home page. Deep links are usually desirable when linking from one site to another, because they link directly to the relevant information rather than the usually more generic home page.

Descriptive text - Descriptive text is important because some search engines use the description in the description meta tag. Some search engines generate their own description from text on the page that appears in proximity to the search phrase.

Domain - The name given to the address of a web site and may include a variety of extensions such as .com, .edu, .gov, and .org.

Doorway Page or Gateway Page - A specially created web page that is designed to rank highly on a particular search engine, most often for commercial purposes. Doorway pages are considered a deceptive practice (form of spamming) and may result in a penalty by most search engines.

Dynamic Content or Dynamic Web Page - Information on web pages that changes automatically, in response to different contexts or conditions. The content may be text, images, form fields, etc.

Entry Page - Any page by which a visitor enters your website.

Exit Page - Any page where a visitor leaves your website.

FAQ - Frequently Asked Questions. FAQ pages are commonly found on most websites and answer questions about ordering and shipping, or specific product information.

Frames – A technique allowing web designers to display two or more pages in the same browser window. Web pages using frames are often not indexed properly by search engines, meaning that the page is unlikely to rank highly in search engines. Frames are not a recommended method of setting up a website, unless the NOFRAMES tag is used.

Google Bot - The name given to the crawlers that index pages into the Google index, or master web site directory which Google uses to display its results.

Header tags – An HTML tag used to enclose the headings or subtitles of text on a page. Headings or headers provide a useful clue to the search engines what the important content on a page is. Therefore, it is often recommended that header tags should contain important keywords a website is trying to be found for.

Hidden Text – A deceptive practice in which content on a web site is invisible to human visitors but readable by search engine spiders. Examples may include making text on a page the same color as the background on a page, to inflate the keyword density without affecting the visual appearance. Use of hidden text will result in a penalty in all major search engines.

Inbound Link or Incoming Link - A link from another website to your website.

Index - The database of a search engine or directory in which data is stored, updated and retrieved.

JavaScript - A programming language commonly used in website development. Judicious use of JavaScript is recommended because most search engines are unable to access and read the text contained within JavaScript, making that content invisible in a sense to search engines.

Keyword - A word or phrase that is used as a search term in a search engine. Optimizing a site involves researching the keywords or phrases that users enter in order to find web sites, and then including those terms in the content of the site where appropriate.

Keyword Density – The repeated use of keywords or search terms in an optimized page as compared to the content not containing the keyword or phrase. Search engines consider keyword density in determining the relevance of a particular page to the search query in question, although there is no consensus on what number an optimum keyword density should be.

Keyword Frequency – A measure of how often a keyword appears in optimized content. Keyword frequency is but one factor to consider in looking at how well an optimized page will rank in search engine results pages. Repeating a keyword too often in a page can be considered a spammy, deceptive practice and may result in a penalty.

Keyword Research – A first step in website optimization, keyword research looks at the particular words and phrases user enter to search for products and services online. Knowing the right keywords to use allows the content writer to compose content that includes the phrases.

Keyword Stuffing – The act of including an overabundance of repetitions of a keyword or phrase in a website. This is generally a deceptive practice aimed at artificially inflating a site’s relevance to search engines.

Link Farm - A group of websites that are interlinked to each other. Link farming is a form of spamming due to manipulation of the importance search engines place on linking. It is far better to put effort into natural, relevant, high quality links than to buy or exchange links with link farms.

Link Popularity – Incoming links to a site are considered a vote of confidence or popularity for a website, and many search engines use a site’s link profile as a factor in their ranking system. The importance of each incoming link is weighed based on the authority of the other sites, and if the content of the other site is related to the content of the site it is linking to.

Meta Description Tag - The description tag provides a short description of the contents of the page for use in some search engines. This is often the text that is displayed when the page appears in the serps. Including keywords in the Meta Description Tag is generally considered good SEO (search engine optimization) practice, although depending on the technical structure of the site and the search engine in question it may not play a role.

Meta Tag - An HTML tag placed within the header area of code for a web site. This information does not appear as a visible part of the web site but can assist search engines in indexing the site’s content. However, like Meta description tags, their importance is debatable due to their ability to be misused and ignored by search engines.

Optimization or search engine optimization (SEO) - Changes made to the content and code of a web site with the goal of increasing it's rankings in search engine results pages and directories. Changes may include rewriting the site’s written content, adding or altering page titles or Meta tags, analyzing the site’s technical structure, and building incoming links from other quality sites.

Outbound Link or Outgoing Link – Links coming from your website and going to another website.

PageRank or PR - The name given to Google's link popularity measuring system, from the last name of one of Google’s founders, Larry Page. PR measures the quantity and quality of incoming links. Sites with higher PageRank generally place higher in search engine results pages (serps) than sites with lower PageRank.

Reciprocal Link or Link Exchange - Two sites agree to link to each other.

Relevance - A subjective measure of how well a web site matches with the intentions of the user who searched for the information. Search engine algorithms place great importance on relevance, and weigh a site’s relevance to the search at hand in order to place the most relevant sites higher up in the serps.

Search Engine - A search engine is an online database of resources and information contained on the Internet. The search engine indexes (catalogs) web pages and documents, stores the results, and makes them available when users search based on the factors in the algorithm. The top three major search engines are Google, Yahoo!, and Ask.com (formerly MSN).

Search Engine Marketing (SEM) – An umbrella term which includes on-page search engine optimization practices, and online marketing methods of driving traffic to a site. SEM includes achieving higher rankings in results through optimization as well as paid advertising campaigns.

Search Engine Optimization (SEO) - Changes made to the content and code of a web site with the goal of increasing it's rankings in search engine results pages and directories. Changes may include rewriting the site’s written content, adding or altering page titles or Meta tags, analyzing the site’s technical structure, and building incoming links from other quality sites.

Search Engine Placement – A site’s position in the search engine results pages, as well as the efforts made to improve that placement, similar to optimization.

Search Term - A word or phrase used entered into a search engine search bar in order for a user to receive information about that word or phrase from web sites.

SERP or search engine results page - The list of search results that are returned by a search engine in response to a search query, with the most relevant results placing higher on the page.

Spamming – An umbrella term for any deceptive practice which is designed to mislead consumers for commercial purposes, or artificially inflate a site’s rankings in the search engine results pages. Examples of spam or spamming include keyword stuffing, hidden text, or the practice of sending unsolicited bulk email. Most search engines will penalize a site they find to be engaging in spam techniques.

Spider - An automated program that follows links to visit web sites to index or catalog them for a search engine or directory. The contents of the web pages are then stored in a searchable database.

Title Tag - An HTML tag which should contain keywords for the page. The title tag is probably the most important factor in determining the relevance of a web site, because it should be descriptive of what the whole page is about.