Image map -
A GIF or JPEG image with more than one linking hyperlink. Each hyperlink or hot spot can lead to a different destination page.

Impression -
A measurement of responses from a Web server to a page request from the user browser, which is filtered from robotic activity and error codes, and is recorded at a point as close as possible to opportunity to see the page by the user. If an ad is displayed 1,000 times, that is considered to be 1,000 impressions.

In-banner video -
A Video delivered as part of (inside of) the display ad creative for a given placement rather than initiating the use of a Video player.

Inbound link -
An inbound link is a hyperlink to a particular Webpage from an outside site, bringing traffic to that Webpage. Inbound links are an important element that most Search engine algorithms use to measure the popularity of a Webpage.

Independent Trading Desk (ITD) -
A third party company that licenses and supports DSP technology to act as a trading desk for Advertisers/Agencies.

Influencers -
A person or group of people who have a strong influential presence on social media and who are often targeted by marketers as social media brand advocates.

Initial Dimension -
The original width and height (in pixels) (( E.g. 728×90) of an expanding ad, typically matched to the placement dimensions. Expanding ads are designed to expand to a dimension larger than the initial dimension ( E.g. 728×360).

Initial File Load -
The size of the creative file(s) for an ad, measured in KB or MB, that load along with (inline with) the Webpage files that load when a user first initiates a page load. The initial file load size of an ad is limited in order to preserve the page load performance and thus the user’s web browsing experience.

Instant messaging (IM) –
A technology that enables real-time, text-based communication between two or more participants over the Internet or some form of internal network/intranet. The synchronicity of the communication is what separates chat and instant messaging from e-mail. In certain cases Instant Messaging involves additional features, i.e. to see the other party by using Webcams, to talk directly for free over the Internet, or to send messages to people not currently logged on (offline messages). (See Real Time).

Interactive advertising -
Online (including Display (banners), Sponsorship, Email, Search, Video, Classified, Social Media Marketing, Etc.); Mobile (SMS, MMS, Applications, Content, Etc.), and Gaming.

Internal traffic -
Company-internal traffic should be disclosed on a disaggregated basis. If company-internal traffic is material to reported Audience Reach Measurements and does not represent exposure to content or advertising that is qualitatively similar to non-internal users, it should be removed from reported counts. Additionally, all robotic or non-human audience activity that arises from internal sources (for example, IT personnel performing testing of content should be removed).

Interstitial ads -
Ads that appear between two content pages. Also known as transition ads, intermercial ads, splash pages and Flash pages. (See Splash Page).

Invalid clicks -
Invalid Clicks can arise from numerous situations based on internal quality guidelines of either or both the Publisher or Publisher’s Agent. Additionally, the Advertiser or Advertiser’s Agent can make assessments of Click validity and bring these assessments to the attention of the Publisher or Publisher’s Agent. In general, Click activity determined to be invalid should be removed from counts to arrive at valid click activity. Invalid Clicks arising from suspected “click fraud” are a sub-component of Invalid Clicks. (See Click Fraud).

Invisible Web -
A term that refers to the vast amount of information on the Web that isn’t indexed by Search engines.

IP address -
Internet protocol numerical address assigned to each computer on the network so that its location and activities can be distinguished from other computers. The format is ##.##.##.## with each number ranging from 0 through 255 (e.g. 125.45.87.204)

ISDN (Integrated Services Digital Network) -
High-speed dial-up connections to the Internet over ordinary copper phone wires. DSL has in large part replaced ISDN. (See DSL).

ISP (Internet Service Provider) -
An organization that provides access to the Internet. An ISP can be a commercial provider, a corporate computer network, a school, college, university, or the government.