In a nutshell, the term covers a variety of technologies used to prevent adverts appearing on internet-connected devices.
They are already widely used on PCs, where the most common technique is to install a browser plug-in, but until recently were relatively rare on smartphones and tablets. Once installed, web pages should be decluttered of distracting content.
Pages should also load more quickly, mobile data allowances should come under less strain and mobile device batteries can also last longer between charges.
However, one consequence is that websites can see a drop in revenues, causing them to start charging for content or paying for technologies that frustrate the ad-blockers' efforts.