Ad filtering or ad blocking is removing or altering advertising content in a webpage. Advertising can exist in a variety of forms including pictures, animations, embedded audio and video, text, or pop-up windows and can employ autoplay of audio and video. It is a known problem with most web browsers, including Firefox, that restoring sessions often plays multiple embedded ads at once. All browsers offer some solution to the problem, either by targeting technologies that are used to deliver ads, targeting URLs that are the source of ads, or targeting behavioural characteristic of ads.
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