ExploreActivity is a potentially unwanted application (PUA) installed through a fake Adobe Flash Player without the user’s knowledge. It promises to enhance one’s browsing experience but it is actually an adware which will attempt to commandeer your browser search and homepage to a fake one. It will also generate and spam unwanted advertisements on your screen in the form of pop-ups, coupons, and banner ads. Lastly, it may as well prevent you from changing your settings back. You have to remove ExploreActivity immediately before it further damages your Mac.