Is the article you're reading now worth seeing an ad for?
If you're reading this column on a phone or a PC, the ads you see around the article may soon force you to make some choices.
Last week, the mobile operator Three said that it was going to start blocking online ads at a network level.
It will start this in its UK and Italian mobile operators, while the Irish operator will "watch and see" how things progress with the move.
Three isn't alone. Digicel, the Caribbean mobile operator run by Denis O'Brien, has also pledged to filter out online ads at a network level.
And more mobile operators are set to follow. The company that both Digicel and Three are using to block ads, Shine, says that it is negotiating with dozens more operators to achieve the same effect.
This operator's move to block ads is of significant concern to publishers.
According to research from Dublin firm Pagefair and Adobe, one in five people now use some sort of ad-blocking app or technology to stop ads appearing on their phones or PC screens. Commercially, Adobe and Pagefair estimate that it is costing publishers up to €20bn in ad revenues each year.
Three says that it is introducing the ad blocking filters because of the growing slice of customers' monthly data consumed by ads. This stands anywhere between 20pc and 50pc.
Digicel's rationale is a little different, with Denis O'Brien having previously objected to Google and Facebook 'getting a free advertising ride' on network operators' infrastructure. He says he wants such web giants to start paying operators in a new revenue-sharing model.
But publishers don't see things in the same way. Ads are the lifeblood of their commercial model. If ad blocking becomes universal, many will go out of business.
So some are fighting back.
'The New York Times' is to consider introducing technology that can detect when an ad blocker is being used by an online reader. It will then cut the reader off.
"Trying to use and get benefit of the Times' journalism without making any contribution to how it's paid is not good," said the newspaper's chief executive, Mark Thompson, this week.
"In the end, they're not really helping pay for what they consume. This stuff is not made for free."
Other major publishers have already introduced this type of anti-ad blocker strategy. 'Forbes' won't let desktop visitors using ad blocking apps past its front page, displaying a message that tells them they must disable the ad blocker to continue reading.
Wired.com has just introduced the same system, with a twist: they can continue using ad blockers if they pay $1 per week.
"We know that there are many reasons for running an ad blocker," says the technology publication's open letter to readers.
"We want to offer you a way to support us while also addressing those concerns."
Ads can be a real pain. Aside from the data they use, they also slow access to web pages, sometimes considerably. But we are coming to a point of reckoning where people will soon have to decide whether the service they want to access 'for free' is worth seeing ads for.