An impression is one single display of a PPC advert relating to a particular search term. The advertiser does not pay per impression, only per click.

An Inbound Link is a direct link to your site from outside. In the very early days of the Internet these were vitally important as a way of navigating the web. These days they are just as important but for a different reason. Page Rank from Google takes into consideration the number and quality of inbound links as part of its analysis of your website.

The Internet Protocol Address, or IP Address, is a collection of numbers eg. 216.239.51.99. It can be tracked back to a specific computer and can be used for Geo-Targeting to produce localised results.