Firefox has no dedicated ad blocker per say, but it does have built-in tracking protection which has a side effect of blocking some ads. To see what Enhanced Tracking Protection (ETP) blocks, check out the article: [[Trackers and scripts Firefox blocks in Enhanced Tracking Protection]]. Set ETP to '''Strict''' mode to block tracking content in all windows whereby ads are considered a form of tracking content. By default, ETP is set to '''Standard''' mode which only blocks tracking content in Private Windows. Be mindful that ETP may not block all ads so it's still advisable to pair ETP Strict mode with a reputable content blocker add-on (such as [https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/ uBlock Origin]) for the best experience.