Glossary of terms that may help

Here is a the beginning of a glossary of SEO terms. I hope they help:-

AdSense: A Google product. Adsense is a way for publishers of all sizes to display Google ads on their site and earn money. There are several different ad units and multiple different ad sizes. The adsense system lets you manipulate the code so that the advertisements suit the layout and design of your site. If using content matching advertisements ads that appear are related to what your visitors are looking for on your site, this then allows you to monetize and enhance your content pages.

AdWords: Another Google product. Adwords is a very effective way of advertising your wares on the net. The advertisements appear on a CPC (Cost Per Click) system. Meaning you do not pay every time your advertisement appears but rather you pay per click on your advertisement

Agent Name: This is the name of the Crawler/spider that is currently visiting a page. Spider is a robot sent out by search engines to catalogue websites on the internet. When a spider indexes a particular website, this is known as 'being spidered'. 
Algorithm: Operational programming rules that determine how a search engine indexes content and displays the results to its users.

Alt Tag: The alternative text that the browser displays when the surfer does not want to or cannot see the pictures present in a web page. Using alt tags containing keywords can improve the search engine ranking of the page for those keywords.

Cloaking: The process by which your site can display different pages under different circumstances. It is primarily used to show an optimized page to the search engines and a different page to humans. Most search engines will penalize a site if they discover that it is using cloaking.

Comment Tag: The text present within the <!-- and --> tags in a web page. Most search engines will ignore the text within the Comment Tags.

Directory: A site containing links to other sites which are organized into various categories. Examples of directories are Yahoo!, Open Directory, LookSmart etc.

Doorway page : A page which has been specially created in order to get a high ranking in the search engines. Also called gateway page, bridge page, entry page etc.

Dynamic Content: Automatically changing content ona website that is based on a database or user information. Search engines will index dynamic content in the same way as static content unless the URL includes a ? mark. If no paremeter it may be ignored

Frames: An HTML technique allowing web site designers to display two or more pages in the same browser window. Many search engines do not index framed web pages properly - they only index the text present in the NOFRAMES tag. Unless a web page which uses frames contains relevant content in the NOFRAMES tag, it is unlikely to get a high ranking in those search engines.

Heading Tags: A paragraph style that is displayed in a large, bold typeface. Having text containing keywords in the Heading Tags can improve the search engine ranking of a page for those keywords.

Hidden Text: Text that is visible to the search engines but is invisible to humans. It is mainly accomplished by using text in the same color as the background color of the page. It is primarily used for the purpose of including extra keywords in the page without distorting the aesthetics of the page. Most search engines penalize web sites which use such hidden text.

Image Map: An image containing one or more invisible regions which are linked to other pages. If the image map is defined as a separate file, the search engines may not be able to index the pages to which that image map links. The way out is to have text hyperlinks to those pages in addition to the links from the image map. However, image maps defined within the same web page will generally not prevent search engines from indexing the other pages.

JavaScript: A scripting language commonly used in web pages. Most search engines are unable to index these scripts properly.

Keyword: A word or phrase that you type in when you are searching for information in the search engines.

Keyword Frequency: Denotes how often a keyword appears in a page or in an area of a page. In general, higher the number of times a keyword appears in a page, higher its search engine ranking. However, repeating a keyword too often in a page can lead to that page being penalized for spamming.

Keyword Prominence: Denotes how close to the start of an area of a page that a keyword appears. In general, having the keyword closer to the start of an area will lead to an improvement in the search engine ranking of a page.

Keyword Weight: Denotes the number of times a keyword appears in a page as a percentage of all the other words in the page. In general, higher the weight of a particular keyword in a page, higher will be the search engine ranking of the page for that keyword. However, repeating a keyword too often in order to increase its weight can cause the page to be penalized by the search engines.

Link Popularity: The number of sites which link to a particular site. Many search engines use link popularity as a factor in determining the search engine ranking of a web site.

Meta Description Tag: The tag present in the header of a web page which is used to provide a short description of the contents of the page. Some search engines will display the text present in the Meta Description Tag when the page appears in the results of a search. Including keywords in the Meta Description Tag can improve the search engine ranking of a page for those keywords. However, some search engines ignore the Meta Description Tag.

Meta Keywords Tag: The tag present in the header of a web page which is used to provide alternative words for the words used in the body of the page. The Meta Keywords Tag is becoming less and less important in influencing the search engine ranking of a page. Some search engines ignore the Meta Keywords tag.

Meta Refresh Tag: The tag present in the header of a web page which is used to display a different page after a few seconds. If a page displays another page too soon, most search engines will either ignore the current page and index the second page or penalize the current page for spamming.

Pay Per Click Search Engine: A search engine in which the ranking of your site is determined by the amount you are paying for each click from that search engine to your site. Examples of pay per click search engines are Overture, HootingOwl etc.

Robot: In the context of search engine ranking, it implies the same thing as Spider. In a different context, it is also used to indicate a software which visits web sites and collects email addresses to be used for sending unsolicited bulk email.

Robots.txt: A text file present in the root directory of a site which is used to control which pages are indexed by a robot. Only robots which comply with the Robots Exclusion Standard will follow the instructions contained in this file.

Search Engine: A software that searches for information and returns sites which provide that information. Examples of search engines are AltaVista, Google, Hotbot etc.

Search Engine Placement: The practice of trying to ensure that a web site obtains a high rank in the search engines. Also called search engine positioning, search engine optimization etc.

Spider: A software that visits web sites and indexes the pages present in those sites. Search engines use spiders to build up their databases. Example: The spider for AltaVista is called Scooter.

Title Tag: The contents of the Title tag is generally displayed by the browser at the top of the browser window. The search engines use the Title tag to provide a link to the sites which match the query made by the user. Having keywords in the Title tag of a page can significantly increase the search engine ranking of the page for those keywords.