Click-through rate

Click-through rate or CTR is a way of measuring the success of an online advertising campaign. A CTR is obtained by dividing the number of users who clicked on an ad on a web page by the number of times the ad was delivered (impressions). For example, if a banner ad was delivered 100 times (impressions delivered) and one person clicked on it (clicks recorded), then the resulting CTR would be 1 percent.

Banner ad click-through rates have fallen over time, currently averaging much less than 1 percent. In most cases, a 2% clickthrough rate would be considered very successful. By selecting an appropriate advertising site with high affinity (e.g. a movie magazine for a movie advertisement), the same banner can achieve a substantially higher CTR. Personalized ads, unusual formats, and more obtrusive ads typically have higher click-through rates than standard banner ads.

CTR is most commonly defined as number of clicks divided by number of impressions and generally not in terms of number of clicks divided by the number of persons who clicked. This is an important distinction. As a person clicks a single advertisement multiple times, the CTR increases using the former definition, whereas the CTR doesn't change using the latter definition.

Origins of Goto.com

Goto.com was an Idealab spin off and was the first company to successfully provide a pay-for-placement search service.

In February 1998, GoTo offered advertisers the option of bidding on how much they would be willing to pay to appear at the top of results in response to specific searches. The bid amount was paid by the advertiser to Goto every time a searcher clicked on a link to the advertiser's website. By July 1998, advertisers were paying anything up to a dollar per click.

GoTo's business model was based on the idea that its paid listings would make it more relevant than other services, especially for general searches, and web sites that pay more are probably better sites. A similar service had been offered by Open Text in 1996, but this precipitated outcries and bad publicity because searchers at the time did not want the search process more commercialized.

In contrast, GoTo's pay-for-placement model was very successful. Commentors theorised that the web had matured in the intervening two years, and these type of economic models were more acceptable since the web was no longer just a place for academic research, but also a place for buying products. GoTo founder Bill Gross speculated at the launch that GoTo would succeed because, as a relatively new service, it had no reputation to taint with paid listings, unlike Open Text.

On October 8, 2001, Goto.com, Inc. renamed itself Overture Services, Inc.GoTo's chief operating officer Jaynie Studenmund said "We also felt it was a sophisticated enough name, in case our products expand."

Through partnerships, Overture enabled portals such as MSN and Yahoo! to monetize the hundreds of millions of web searches made each day on their sites. Indeed, these partnerships proved highly lucrative, and in a period otherwise marked by dot-com failures, Overture became a substantial profit driver for portals like Yahoo!

This success enabled Overture to acquire web sites such as AltaVista and AlltheWeb.

Pay per click

Pay Per Click (PPC) is an Internet advertising model used on search engines, advertising networks, and content sites, such as blogs, in which advertisers pay their host only when their ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system.

Websites that utilize PPC ads will display an advertisement when a keyword query matches an advertiser's keyword list, or when a content site displays relevant content. Such advertisements are called sponsored links or sponsored ads, and appear adjacent to or above organic results on search engine results pages, or anywhere a web developer chooses on a content site.

Although many PPC providers exist, Google AdWords, Yahoo! Search Marketing, and Microsoft adCenter are the three largest network operators, and all three operate under a bid-based model. Cost per click (CPC), varies depending on the search engine and the level of competition for a particular keyword.

The PPC advertising model is open to abuse through click fraud, although Google and other search engines have implemented automated systems to guard against abusive clicks by competitors or corrupt web developers.