Sometimes when you're browsing the web, you get more than you expected.

Like when you visit a website and a video starts playing aloud automatically and you can't find the mute button to turn it off.

Well, the days of these annoying auto-play video ads may be numbered: Google and Apple have announced ad-blocking features that will likely be rolled out in the next year.

What is Apple doing?

Last week at Apple's annual developers conference, the company unveiled a new feature in Safari that will block auto-play videos that play sound.

Safari will detect websites that automatically play videos and pause them so users can decide whether they want to watch the ad or not.

The feature will be added to Safari in Apple's upcoming desktop operating system — macOS High Sierra.

What is Google doing?

Google has publicly stated that, starting early next year, it will introduce changes to its Chrome web browser that will disable certain types of ads on desktop and mobile.

Google isn't calling this change an ad-blocker, but it's essentially an ad-blocker: it will only filter out certain types of advertisements that Google believes creates a bad user experience. That includes auto-play video ads with sound.

It also includes pop-up advertising, and so-called prestitial countdown ads. These are the ads that show a countdown where you have to wait 10 to 30 seconds before you're allowed to see the content you're actually interested in.

Google will offer publishers a tool called Ad Experience Reports which will help them analyze their websites to identify problematic ads and potential issues with this new version of Chrome.

The new version of Chrome that filters ads will be rolled out next year.

Why do videos auto-play like this, anyway?

The short answer is that they can be very effective in getting people's attention.

This type of ad is sometimes called an "outstream" video. They're also sometimes called "native video" ads or "in-read" video.

There are a couple of different variations, but basically, we're talking about any video ads that you see on a primarily non-video web page, such as a news article.

Sometimes the ads play as soon as you load a web page. Other times, they wait to play until you've scrolled past them or moused over them.

Some of these ads play automatically but with the sound muted. Others play with the sound up, which can be startling, or annoying, or both.

Publishers like these types of video ads because they can be very lucrative — much more lucrative that a traditional text or image ad.

But many consumers don't like this type of ad, especially the type that plays audio automatically.

How is the advertising industry responding to these changes from Apple and Google?

SlimCut Media is an international technology company that works with The Globe and Mail, The Toronto Star and the National Post to deliver outstream ads, which auto-play video, but they auto-play with the sound off.

Damien Véran, the company's president, says so-called premium content sites don't need to worry about Google and Apple's changes. But smaller sites, especially clickbait-type sites, could be hit hard if Google and Apple block videos that auto-play with sound, which many of those types of sites use.

Safari will detect websites that automatically play videos and pause them so users can decide whether they want to watch the ad or not. (CBC) "If they don't have this capability anymore, then it's a lot of revenue that's going to be disappearing," Véran said.

Will Apple and Google's efforts be effective in getting rid of auto-play video?

In the long-term, it's hard to say.

In the short term, once the ad-blockers are released, I suspect these tools will be effective in reducing the number of loud audio interruptions many people experience on websites.

But anytime we talk about ad-blocking technology, there are two important things to remember.

The first is that ads pay for much of the content we see online.

These auto-play video ads (annoying as they can be) are a particularly lucrative source of revenue for the publishers who create the content we consume online.

If these ads go away or become less effective, publishers will search for other revenue sources, which could well be more annoying or invasive than outstream ads.

The other thing to keep in mind is that the story of ads and ad-blockers is fundamentally a game of cat-and-mouse.

Yes, Google and Apple are big companies with popular web browsers, and they may have the upper-hand for a while with these tools. But online advertisers can be very inventive and crafty, and I don't think it will be long before publishers and ad companies start developing products that circumvent these autoplay blockers.

But if the web seems a little bit quieter in the next couple of months, you'll know why.