A code within the HTML header that contains information such as keywords and descriptions about the Web page specifically for Web crawlers or search engine robots/spiders. Normally it is not visible to the viewer.

Most simply, data that describe other data.

In regards to a Web site, metadata is information about a specific Web page -mainly the title, descriptions, and defined keywords, and may also include abstracts and other pertinent Web site information.

Keywords or phrases that describe data on a Web page and are chosen to optimize the page for search engines.

An individual Web site housed within a larger Web hosting site, usually with a specific or niche focus. Example: a corporate or consumer-focused blog that is an element in a company's primary Web site.

An extension of the original email protocol that allows email to contain non-text messages, such as pictures or files.

A content-type that allows email to include multiple kinds of content, such as text, HTML, and binary attachments.

A list of links found at the top, bottom or side of a Web page that allow visitors to find any page within a given Web site; or graphical elements, including bars and buttons, that move visitors from one page to another.

The text on a navigation bar or button that describes the destination page.

A person making his/her first visit to a Web site or page.

A link attribute proposed by Google to instruct search engines not to follow a particular link, potentially resulting in lower rates of link spam on blogs. However, some argue that the practice diminishes the conversation taking place between sites.

The population of readers, especially subscribed readers of email communications and registered Web users.

"Opened" messages include HTML emails that have been viewed in a preview pane or fully opened in the email client, as long as images have been enabled. Opens are generally tracked by inserting a small clear image in an HTML message. When a message is opened and images are enabled, the image calls the server and the message is then counted as an open. Text messages cannot be tracked as opened because they cannot include images.

The total number of emails opened divided by the total number of emails delivered (multiply this number by 100 to express the result as a percentage). 

The action a person takes when he or she actively and explicitly requests, by email or other means, to receive email communications. (Also see Double Opt In)

The action a person takes when he or she chooses not to receive email communications. It requires a Web-based mechanism by which people can ask to be removed reliably from an email list. This request must be honored within ten days. (Also see Unsubscribe Request)

Traffic or search results that are a product of a search engine’s algorithm, rather than paid advertisements. Organic search engine ranking is a page rank based on organic, or natural search. (See Paid Search)

A measurable unit of content housed on a Web site.

A Web analytics methodology for tracking and analyzing Web site activity and visitors' online behavior by counting how many times a specially inserted tag or script on a page gets called.

The text that describes the content of a Web page. The page title is displayed as a link in a list of search engine results.

A measurable instance in which a Web page was viewed by a human visitor. Page views are usually expressed as the number of times a page is viewed over a certain time.

This metric tracks a visitor's activity by the number of pages viewed in that visit. Divide the number of page views by the number of visits in the reporting period.

An advertising platform driven by purchase of specific keywords in order to increase a page's chance of being returned high in the search results.

The practice of building an email such that the recipient feels it is a more personal experience. Personalization can include a number of things, such as mail merging a name into the body copy, referring to previous purchases, or more dynamic content insertions based on demographic fields.

A digitally recorded program, made available in a downloadable format for listening on personal computers or portable devices such as iPods or mp3 players.