AdCenter refers to Microsoft's Cost-Per-Click ad network. Due to its relative newness in the industry of online marketing, it only has a limited market share as compared to Google Adwords.

AdSense is Google's contextual advertising network. Website owners can enroll in this ad serving program to allow text, image, and video advertisements administered by Google to be on their sites. Revenue is generated on a per-click or per-thousand impressions basis and publishers share the profits from those ad clicks with Google.

AdWords refers specifically to Google's advertisement and link auction network. AdWords offers PPC advertising and site-targeted advertising for text and banner ads at the local, national, and international level.

A click generally refers to a search engine campaign, where a click would indicate that a user clicked on an ad or listing and was delivered to a website. Thus, a click on an ad results in a hit, or a visitor, to a web site.

Contextual Advertising is the term used to describe advertising programs that generate and display relevant advertisements on a site based on the specific content of that webpage. Google Adsense was the first contextual advertising program and remains the most popular one.

A conversion is a measure of a quantifiable goal being achieved on a website. This will of course vary from site to site. It could be a sale transacted, a lead form filled out, or a phone call made to the company. A conversion is the most important metric because it is related directly to revenue generated for the business.

At the technical level, a cookie is a small data file (often URLs, Web addresses, etc.) created by a Web server and stored on a user's computer. The purpose of cookies are to help websites customize a visitor's experience, as well as allow affiliate program managers to track conversions.

CPA stands for "Cost Per Action" and is defined as the cost to an advertiser for a specific action taken by a user in response to an ad. An "action" may be anything from an ad click to buying a product. It is a very useful way to measure the effectiveness of online advertising.

CPC stands for "Cost Per Click". It is the specific amount that an advertiser is charged each time their ad is clicked. Most search ads and contextual ads are sold in auctions where advertisers are charged on a Cost Per Click basis.

CPM stands for "Cost Per Thousand Ad Impressions". This refers to how much an advertiser pays for 1,000 impressions ( page views) of its ad, regardless of the consumer's subsequent actions. CPM is often used to measure how profitable a website is or will be.

CSS or "Cascading Style Sheets" is the language used to describe how an HTML document should be formatted. Both web designers and users often use CSS to create style templates that specify how different text elements appear on a webpage.

CTR is short for "Clickthrough Rate" and refers to the ratio of the number of clicks on an ad compared to the number of views. CTR is helpful in measuring an ad or link's effectiveness, as well as the relevance of a particular traffic source or keyword. Generally, the higher the clickthrough rate the better. Search ads tend to have higher CTRs than traditional banners ads.

Dayparting allows advertisers to adjust bids, or pause and resume campaigns based on the time-of-day or day-of-week. This strategy involves bidding more when your target audience is available and less when they are unlikely to be available.

A deep link is a link that points to an internal page within a website. Deep Link Ratio refers to the number of internal pages which are linked from other website's most targeted relevant page to your most targeted relevant page.

Flash content is the graphic animation used on websites to make them look rich and interactive. However, because flash contains minimal relevant content, search engines have more difficulty indexing and ranking websites that utilize flash content.

Frames is a feature supported by most Web browsers that allows website designers to display two or more pages (frames) in the same browser window. Although this web design technique facilitates consistent site navigation, frames have now been replaced by more effective content site building tools.

"Google Dance" was the informal term used to describe Google's monthly update of its search engine rankings. Now that Google has shifted to a constantly updating index, it no longer relies on this monthly procedure.

A hit is a single view of a webpage, web image or file.

Used generally when referring to Pay-Per-Click campaigns, an impression refers to when your ad is shown on a search results page after being triggered by a user's search query.

A landing page is the webpage that a visitor arrives at after clicking on a link or advertisement. It is also referred to as a destination page, destination URL, or target URL.

Your guide to search engine marketing.

Link building is the process of getting high quality websites to link to your website in order to increase link popularity and pagerank. Search engines consider websites with high quality inbound links to be more relevant, authoritative, and trustworthy, which helps boost their rankings in the search results.

Long tail keywords are keyword phrases (normally composed of 3 to 4 keywords) that are more precise and specific, and therefore have a higher value. When long tail keywords are searched they are much more likely to convert to sales than more generic keywords.

One-way links are links to your site from sites that do not receive a link from your site. These are much more effective in increasing link popularity than reciprocal links because they show that other sites want to link to your site without receiving an inbound link in return.

Also known as "natural" rankings, these are the search results that are supposed to be the most relevant results to the search query in question. Unlike PPC, you cannot control where you show up, and you do not pay each time a user clicks on the link. The rankings are based off of hundreds of factors, including the content on the site, the links from other sites to that site, the age of the site and much more. Also unlike the sponsored links, these rankings can take years to achieve, and the incumbent sites have a huge advantage over newcomers.

Founded in 1997, Overture is the pioneer of search marketing and PPC advertising. In 2003 it was bought by Yahoo and subsequently branded as Yahoo Search Marketing (YSM).

Pay Per Call is similar to pay-per-click advertising, however, instead of clicking a sponsored link, pay-per-call ads display a toll-free telephone number that the person can call. The advertiser therefore receives a phone call instead of a visitor who clicks on their link and is then directed to their webpage.

Also known as "sponsored links" or "paid search", these are the text ads on the top and down the right side of the search results pages of nearly every major search engine. Each time a web searcher clicks one of these links, the advertiser pays the search engines, from $.01 to $10 or more (the average is around $1-2 per click for positioning on the top of the page).

PageRank is the index used by Google to rank websites on a scale of 0 to 10. This score is determined by Google using a complex logarithmic scale, based on a variety of factors including link popularity.

A page view is a single page being viewed a single time by a single IP address. Thus, one unique visitor resulting from one click could explore a website, visit ten pages and tally 10 page views.

Pay-Per-Action advertising is a new pricing model that enables advertisers to pay only when specific actions that they define are completed by a visitor on their site. For example, instead of paying for clicks or impressions, an advertiser may choose to pay only when a user makes a purchase or signs up for a newsletter.

A quality score is a measure used by Google to assess the quality and relevance of your ads and determine your keyword status, minimum CPC bid, and ad rank. The score is determined by your keyword's clickthrough rate and the relevance of your ad text, keyword, and landing page.

A query is the particular word, phrase, or group of words that a searcher enters into a search engine.

Reciprocal links are links to another website placed on your site in exchange for links to your site placed on their website. Quality reciprocal link exchanges can be an effective way to build link popularity and boost search engine rankings if done effectively, however, reciprocal links offers of low quality should be avoided.

A referrer is the source from which a particular website visitor came from.

ROAS stands for Return On Advertising Spending and represents the dollars earned per dollars spent on advertising. ROAS is computed by dividing revenue derived from the ad source by the cost of that ad source.

ROI stands for Return On Investment and is a measure of how much return you will receive from each marketing dollar.

RSS stands for Rich Site Summary or Real Simple Syndication. It is a method of sharing content among different websites. Sites can syndicate "feeds" (content) and users can use an application known as an RSS reader to download these feeds.

Search Engine Marketing is the broad term that encompasses all efforts with regard to achieving leads and sales from the search engines: PPC Management, SEO, and landing page optimization generally all fall under the umbrella of Search Engine Marketing, though the phrase is used quite liberally and in a variety of contexts.

Search engine optimization is the process of increasing a website's organic rankings. The process is complex and time-consuming, and includes improving website usability, content building, link building, social media and much more.

Search Engine Submission refers to the act of telling ("submitting") the search engine that a website exists; it is basically a request for the search engine to visit, index and rank the site according to relevant keywords. Several years ago, with hundreds of search engines competing for market share, it was a valuable service on its own. More recently, Search Engine Submission is a very small - and many times unnecessary - part of a Search Engine Marketing effort.

SERP stands for Search Engine Results Page and refers to the page on which the search engines display the results for a particular search query.

A sitemap is a visual model of the pages of a website. It is used to help search engines navigate through your website.

A unique visitor is a count of the number of distinct IP addresses that have accessed a webpage or website in a period of time. So in a given month, a website may have 1,000 visits, and 600 unique visitors, indicating that some of those 600 unique visitors visited the site more than once, totaling 1,000 visits total.

URL stands for Uniform Resource Locator and refers to the unique web address of any webpage.

Viral Marketing includes self-propagating marketing techniques. Common channels of transmission include email, blogging, and word of mouth.