# Web Science/Part2: Emerging Web Properties/Web Search Ecosystem/Introduction to Online Advertisement/script

Online advertising, also called Internet advertising, is a form of advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes
* email marketing,
* search engine marketing,
* social media marketing,
* many types of w:display advertising (including w:web banner advertising),
* and w:mobile advertising.
Like other advertising media, online advertising frequently involves both a publisher, who integrates advertisements into its online content, and an advertiser, who provides the advertisements to be displayed on the publisher's content. Other potential participants include advertising agencies who help generate and place the ad and maintain the w:ad server which technologically delivers the ad and tracks statistics. The Ad agencies and their server software act as a trust provider for both the advertiser and the publisher. The biggest add agency is Google with their famous adsense and adwords products.
In the following units (we will not talk about mobile advertising, email marketing, and social media marketing. Instead) we will focus on the main formats of online advertisement and the various payment methods like CPC, CPM, pay per sale and pay per lead. We will also focus on metrics that help the various stakeholders to evaluate their success in the online campaign. You will realize that many concepts in online advertisement are very similar to offline methods in advertisement. But there are some formats which are rather difficult to implement in the offline world. One example of such a method would be w:retargeting where an ad server places a cookie on a consumers computer while he might be browsing the shop of a potential advertiser. If the consumer does not buy anything but surfs on some publisher's website that uses the same ad server the consumers web browser will send the cookie to the adserver. This ad server can now place advertisements of the online shop that has previously been visited by the user inside the website he is currently browsing. The user might be reminded or as it is called retargeted with these products. Even though highly effective this format is not very common since users preserve this format as a harsh intrusion of their privacy.
Another big difference between the offline and online advertising space is that due to tracking technologies on the web the success of an online advertising campaign can be measured very effectively and quickly. In order to do so you will learn about the right metrics like click through rate, conversion rate and bounce rate. Due to this difference (in combination with the technological possibilities of personalizing) online advertising campaigns can be better targeted and be more focused. Also it is easier to test how advertisement campaigns will be preserved by a small group of the targeted consumer audience. That is why online advertisement includes less risk than large scale television and offline advertising campaigns. On the other side evaluating ad campaigns is much more data driven and requires talented experts. Still the high effectiveness might be one reason why the online advertisement market has been constantly growing.