Search Engine Terminology:

Accessibility
In the context of the web, the goal to make web content equally accessible to all users, regardless of software (browser, operating system), hardware, or physical disability.
Alt text
Alternative text is placed in the code for an image or object embedded in an HTML page. Alternative text should be displayed by a browser when the image or object, for whatever reason, is not downloaded or displayed.
Anchor Text
Anchor text is the text used as a link to another webpage or a different place on the current page. In a hyperlink, the anchor text is the visible text of the link.
Authority Page
A web page with many unique, subject specific domains linking into it. The site may be considered an authority on that subject.
Backlinks
See Inbound Links
Bandwidth
The ability of a connection to handle data. Usually measured in bits-per-second. Internet connections commonly vary from a fast modem at about 57,000 bps to many DSL or Cable connections at over 1,000,000 bps.
Blog
The blog originated as an online personal journal available on the web - weB LOG. Although this is still the most prevalent use of a blog, they have come into common use by businesses as a means to share day to day information with their customer base.
Canonical URL
A canonical URL is the preferred internet address for a website. Frequently, two alternate URL's will access the same site: http://www.example.com and http://example.com. This can have a diluting effect on your search engine representation and PageRank. Thus, it is best to use a 301 redirect to force all visitors to one specific URL.
Cloaking
The act of serving different HTML code to different visitors to a web page based on certain criteria.(I hate Google.org)
Clustering
1: a means of grouping search engine results by topic or perceived purpose of pages. The technique finds common terms or phrases and identifies pages as being related by those topics.
2: a way of limiting websites represented in a search engine results page two only one or two listings in order to provide a greater variety of results
Contextual Advertising
Text or image advertising delivered automatically on the basis of the search terms entered or the content of the page you are visiting.
Contextual Search
A search performed with reference to a limited search index. Examples would include site searches, searches limited to a specific topical area, or a search which extracts meaning from a reference source (such as a web page) which influences the results returned.
Cookie
A piece of information sent by a web server to your browser which is stored on your computer. Usually contains information which will identify your preferences or information to that server on your return, such as login information, shopping cart data, or user preferences. Cookies usually expire after a predetermined amount of time or until the browser is closed.
Directory
A human-compiled and subject organized search tool. Most directories use human editors to select the sites they want in their directory - either on a fee-based schedule, or by active selection.
FFA
See Link Farm.
HTTP Status Codes
HTTP status codes are numeric strings delivered to your browser by a server when you request a page. The most common are 200, which confirms that the page expected is present, and 404, which is an error message indicating that the expected page is missing. Other common codes include 301 and 302 redirects.
Inbound links
Hypertext links pointing back to your website. These links can be identified using advanced operators on search engines such as link: or linkdomain:. Also known as "Backlinks"
Internal links
A link in your site which points to another page on your site. Provides internal navigation within your website.
Keywords / Keyphrases
The words or groups of words you want your site to rank highly for when searched in a search engine.
IP address
Every computer connected to the Internet must have a unique address for identification in the network they belong to, known as Internet Protocol (IP) address. It's numeric, with 4 groups of numbers separated by dots. For example 129.107.38.20.
Landing Page
The page a visitor arrives at after following a link to your site. Most commonly used in relation to Pay-per-click or contextual advertising, where you can assign a specific arrival destination for visitors from that ad campaign.
Linkbait
The aim to create content interesting enough or unique enough to prompt extensive inbound linking. Most frequently applied to blogs, but applicable to all websites.
Link Farm
A Link Farm or FFA (Free For All) is a website where anybody can add a link. These sites usually display only the most recent links submitted, in no particular order. Since they have no value to a human visitor, they're considered undesirable by search engines.
Link Popularity
A measurement of the quantity and/or quality of sites which link to your website.
Linking Strategy
An effective method to build and maintain the inbound links to a site in order to achieve your business goals and maximize your search visibility.
Metasearch
Literally, a search of searches. Commonly refers to an internet search tool which submits simultaneous searches to a group of search engines and compiles those results to produce a ranked or clustered results page.
Meta Tag
A type of HTML tag which contains information about the web document itself. Meta means " about this". Typical uses of Meta tags are to describe the content of the page, provide keywords to the page, specify the language of the page, or identify the author.
Off-page Criteria
Indexing rules using data from outside your website, such as inbound links and the anchor text of those links.
On-page Criteria
Indexing rules using data within your web page, such as your content, title tags, keyword use, and internal importance.
Organic SEO
Organic SEO is a technique of improving your results in the free (non-advertising) results on a search engine results page. Organic SEO usually requires an improvement of your site content, infrastructure, or other technical elements of your site.
PageRank
The algorithm developed and patented by Stanford University and Larry Page (co-founder of Google) to rank search engine results. PageRank is a measurement of how useful and relevant a site is to a search term based on the number and relevance of inbound links.
Paying for a specific ranking on a SE results page.
Pay-Per-Click (PPC)
A hyperlinked banner or text link shown in advertising space which is billed by counting the clicks to your web site via the banner or link.
Reciprocal Link
When two websites swap links to point at each other. Trading links with other websites.
Redirect
There are two meaningful types of redirects, frequently referred to by numbers: 301 or 302. These numbers refer to the HTTP status codes which the server returns to your browser when the page is requested. 301 is the permanent redirect, telling the browser (or spider) that the page has been moved for good, and will not return. This tells a search engine to use the redirected URL in the future, and to not spider the old URL. A 302 redirect is for a temporary move, and should only be used for changes which are actually temporary. Using a 302 redirect permanently can be perceived as a form of SEO spam.
RSS
RSS, commonly explained either as Rich Site Summary or Really Simple Syndication, is an XML format for distributing content online. The format contains a listing of links, text, and metadata about the original document.
SEM: Search engine marketing
Using marketing strategies to increase search visibility, including web advertising, link building, and other content marketing.
SEO: Search engine optimization
Using information architecture and web semantics to adjust a web page for optimal machine-readability.
SEP: Search engine placement
A particular location in a search engine results page.
SERP: Search engine results page
A page of results returned by a search engine.
Semantics
The study of, or application of meaning to structure.
Site-wide link
A link which appears on all pages of a website.
Spider
A common term referring to the software which search engines use to follow links finding new sites to add to their search engine indices. Also known as a webcrawler, robot, or 'bot.
Tagging
An organizational system for information which involves characterizing documents according to a group of terms (tags) which represent the content of the document. Used by many social networking and organization tools such as Technorati or Edgeio.
Useability
Optimization of a site to reduce redundancies and maximize ease of access and logic within a site. The attempt to make site navigation intuitive.
Vertical Creep
describes the "invisible tab" behavior of search engines; a method of including search results from other indexes than the one searched. e.g., receiving Google Images results in a search of the main Google search.
Vertical Search
Searching within specialized or subject focused materials. A "vertical search engine" is a term describing search engines which specialize in certain types of data, such as Kosmix, for health information. Certain search utilities, such as Zillow, specializing in real estate data, though vertical search tools, are not necessarily search engines, since they use proprietary databases rather than data gathered from freely searchable web resources.
Viral marketing
Marketing phenomenon that encourages and depends on people to pass along the marketing message. If many people pass the message along, very rapid growth is likely to erupt for the marketed product or person.
Web 2.0
A term applied to the transition of the Internet from a collection of connected websites to a computing platform with rich web applications. Also applied to sites which exhibit the rich web characteristics of the transition.
Web Semantics
The process of applying semantic logic to the code of a webpage. Using the inherent meaning of HTML code to represent the meaning or value of text on a website. See: semantics
Web Spam
Web sites which provide exceptionally low value to visitors. Their principal purpose is commonly to serve as a "carrier" for viruses, malware, adware, or to serve large quantities of low-quality advertising. These web sites frequently clog the search results for popular search terms.
XML
XML stands for eXtensible Markup Language, meaning a language for defining the structure of a document. It is extensible in that it is not restricted to a specific group of tags, like HTML. Instead, you can create a separate document (a document type definition, or DTD) which informs software how the XML document should be read.