Yesterday, one of the largest ad serving platforms on the web, Google’s DoubleClick for Publishers, went down.

Google said the service was back up and running within two hours:

But the news and the result of the outage cost publishers dearly. Business Insider said it cost $1 billion per hour for publishers globally. adAge said while it cost some big time, there were those who benefited from it that were not using DoubleClick.

Many sites, including this one, use DoubleClick to serve ads.

Forum discussion at WebmasterWorld.