Ad rotation is the practice of showing multiple advertisements

Advertising

Advertising is a form of communication used to persuade an audience to take some action with respect to products, ideas, or services. Most commonly, the desired result is to drive consumer behavior with respect to a commercial offering, although political and ideological advertising is also common...

 in a single location on a web page

Web page

A web page or webpage is a document or information resource that is suitable for the World Wide Web and can be accessed through a web browser and displayed on a monitor or mobile device. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext...

. Ads may be rotated with each new page load, within a single page load, or both. Because the ads are placed in the same location, they are typically the same format.

The goals of ad rotation include:

• Allow publishing sites to serve ads for multiple advertisers.
• Keep advertising "fresh". If the ad never changes, users are more likely to ignore it.
• For content-rich sites, increase exposure to advertising by showing multiple ads per page load instead of just one.

Ad rotation software, known as ad rotators, commonly provide features such as the following:

• image management
• display weighting to control the frequency and duration of individual ads
• reporting, allowing advertisers to see how often ads were displayed and clicked
• for service-based ad rotation, management features such as color selection, filtering competitor ads, channel selection (content, video, search, etc.) and payment management

Technical implementation

Technically, ad rotation can be accomplished in multiple ways. The three most common approaches are server-side

Server-side

Server-side refers to operations that are performed by the server in a client–server relationship in computer networking.Typically, a server is a software program, such as a web server, that runs on a remote server, reachable from a user's local computer or workstation...

, client-side

Client-side

Client-side refers to operations that are performed by the client in a client–server relationship in a computer network.Typically, a client is a computer application, such as a web browser, that runs on a user's local computer or workstation and connects to a server as necessary...

 and service-based.

With server-side ad rotation, the ad is selected on the server and the corresponding HTML markup is generated and then served.

Client-side ad rotation typically involves JavaScript

JavaScript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

 of some sort (either straight client-side JavaScript

Client-side JavaScript

Client-side JavaScript is JavaScript that runs on the client-side. While JavaScript was originally created to run this way, the term was coined because the language is no longer limited to just client-side, since server-side JavaScript is now available.-Environment:The most common Internet media...

 or else AJAX

Ajax

- Mythology :* Ajax , son of Telamon, ruler of Salamis and a hero in the Trojan War, also known as "Ajax the Great"* Ajax the Lesser, son of Oileus, ruler of Locris and the leader of the Locrian contingent during the Trojan War.- People :...

 calls to the server.

Service-based ad rotation is similar to client-side ad rotation in that it typically involves placing a small amount of JavaScript in the web page, but the JavaScript calls against a third-party service that provides its own management interface for specifying ad delivery options. Google's AdSense

AdSense

Google AdSense which is a program run by Google Inc. allows publishers in the Google Network of content sites to automatically serve text, image, video, and rich media adverts that are targeted to site content and audience. These adverts are administered, sorted, and maintained by Google, and they...

service is an example of service-based ad rotation.