Internet users in the US are using ad blocking software — almost half of them. They block online ads. To begin with, this was done by those who are technically savvy, but now it has become mainstream. Subscription based services are not affected. It is a big trouble for display ads. Advertising within mobile apps is safe at least currently. Because of this blocking, you must get larger page views to get  the same effect. Could it affect online journalism? Journalism could fund itself from other sources — subscriptions, conferences and native advertising ( e.g. Hulu refuses to play unless you watch the ad ). There are mobile ads. Companies may have to figure out how to get around the ad bloking software. Its a wake up call for online advertisers.