Jump page (also Landing page)
The page that is displayed when a user clicks on an ad.

Lead
Action that doesn’t involve payment, such as filled-out form, free trial signup, or free download.

Log file
A journal file that records all the requests made to a web server over a given time period. Some of the types of data which are collected are: date/time stamp, URL served, IP address of requestor, status code of request, user agent string, previous URL of requestor, etc.

Media
Distribution vehicle. The most used online media is the website.

Mouseover
Process by which a user places his/her mouse over a media object, without clicking. (Source: IAB)

Opt-in
An online process by which a subscriber requests to receive information such as e-mail advertising and newsletters. An opt-in e-mail list is also called a permission-based e-mail list.

Opt-out
An online process (such as un-checking a pre-checked box) by which a user actively chooses not to receive information.