Above the fold is the area in an email or web page where the content can be viewed before scrolling down. Some define it as the location of an ad at the top of a screen. Due to banner blindness, the usual location of ads does not perform as well as ads that are integrated in the content of a site.

Absolute link is a link that shows the full URL of the page being linked to. Absolute links are preferred over relative link paths due to canonicalization and other hijacking issues.

Accessibility is the practice of creating sites that are more accessible or usable for disabled persons particularly the blind. Accessible sites tend to have higher rankings in search results than inaccessible sites primarily because search engines are essentially blind and heavily rely on texts.

An acquisition is a person who not only browses a site but also subscribes to the site, purchases a product from the site, or leaves his or her details on the site - depending on the goals of the website.

The acquisition cost is the total cost of advertising divided by the number of the visitors of the site or the number of customer the site was able to acquire.

An ad broker is a person who sells advertising space on a website.

Ad Centre is a cost per click ad network that is owned by Microsoft.

The ad inventory is the total number of potential views that a page has. This is used for advertising purposes.

Adjacency is the relationship between words in a search engine query. Search engines give sites a higher rank when the words that are searched for appear side by side in the body of text on a website compared to words that are separated by other words that are not included in the search query.

Adjacent searching is also known as proximity search. This is a technique to check the position of terms and match terms that are within the specified distance between keywords. This is often used to get better results in a search query by removing irrelevant matches.

AdSense is a contextual ad based program by Google. It is a way of earning money by displaying Google ads in the pages of your site.

Advanced search is an option in search engines to narrow down the results of a search query based on parameters set by users.

AdWords is Google’s cost per click text based advertising. Most of the ads offered by Google targets keywords and are sold on a cost per click basis in an auction that includes factors such as click through rate and maximum bid.

Affiliate Marketing is a marketing program where in an advertiser gives compensation to affiliates/ members who are able to provide traffic to their site or make a sale on behalf of the advertiser.

The affiliate program link is a sort of identification link that affiliates of a website use to direct other users to the site. Once other users click the link, the affiliate program takes note of it and gives the affiliate a commission based on the goals of the affiliate program - whether to gain a sale, a registration to the site, etc.

The age of a site is often used by search engines to test the validity of a site. If a site is new it would rank quite high because it is viewed as unique and fresh but in the longer run, the rankings of new sites lower and is replaced by older and more trusted sites.

Agent name is the name of a crawler or spider that is currently visiting a page.

Agent name delivery is the method of sending search engine spiders to a tailored page that is different from what other visitors could see. Different pages can be shown using the same URL - a different page can be seen by normal visitors, another page for search engines.

AJAX or Asynchronous JavaScript and XML is a way of designing a web page to be more user friendly and to be able to respond quickly to request made by users without having to reload the entire page. An example of this is Google Maps.

Alexa is a service owned by Amazon.com that can measure the traffic to a website. However, it tends to lean towards sites that are marketing oriented and towards webmaster communities which makes it unreliable. The service is free of charge.