Advertising is the lifeblood of the internet. It's the web's fundamental economic model, with ad revenue underpinning about 90% of everything people see online. But as ad blocking programmes become mainstream on both desktop and mobile, could it herald the end of a free internet?

People don’t like ads, and the success of Spotify Premium shows that they'll pay to avoid them. YouTube is now offering a similar option in the form of YouTube Red, giving users an ad-free experience and exclusive content. How might the loss of commercials impact the future of the ad industry?

Advertising on smartphones can be annoying, with many people frustrated by pop-ups that slow them down and block their screens. But they could become a thing of the past, with Apple's iOS set to allow ad blocking extensions for the first time on mobile versions of its Safari browser.

Advert-blocking browser plugins are growing at a rate of nearly 70% year-on-year. The most popular, AdBlocker, reached 150 million users in June 2014. And if people really are more likely to climb Mount Everest than click a banner ad, what is next for online advertising?