Yahoo and Adobe trial PDFs with ads

The one last corner of the online world that had yet to be filled with banner advertising has finally succumbed.

Adobe, the technology company behind the portable document format, known as the PDF, has worked out a way to allow adverts to appear down the sides of PDF documents.

Technical complexity has meant that emailed documents and website pages in the easily-printable PDF have so far been closed to the sort of contextual advertising popularised by Google, which serves up ads relevant to their subject matter. But Adobe and Yahoo, the internet media company, believe they can turn PDF-based advertising into a lucrative revenue stream.

The pair said yesterday they had begun testing the service, in which Yahoo will scan a PDF document for keywords and then place a banner advert based on those keywords. The adverts would not appear on PDF documents that were printed out, but could be programmed to appear differently each time the file was opened.

Yahoo is second only to Google in terms of the size of its network of advertisers, who pay to have Yahoo serve up their ads on websites and next to search results.

Yahoo and Adobe will share revenue from the adverts with the publisher of the document.

Reed Elsevier and Pearson, the UK-based educational publishers, are among those testing the service. Book and magazine companies who use the PDF format for online or emailed versions of their publications could be among the heaviest users of the new service.

It could also mean that e-books for electronic readers, such as Amazon's recently launched Kindle, could be offered free to users, funded instead by advertising.

"This creates a previously untapped opportunity for advertisers to connect with qualified audiences, while opening new revenue streams for publishers, and helping to deliver additional relevant content to consumers," said Todd Teresi of Yahoo.