Few days ago I opened The Pirate Bay and was astonished to find it full of ads. Sometime later it happened with another site. Finally, I found the problem. AdBlock was stopped. AdBlock is the plugin that must come preinstalled with every browser. It kills (removes) almost all ads from sites. It's easy to use and to customize (add more sites or ads to the block list).
sees the invisible web - tags, web bugs, pixels and beacons. Ghostery tracks the trackers and gives you a roll-call of the ad networks, behavioral data providers, web publishers, and other companies interested in your activity.
Since Firefox for Mac is awful. I'm using Chrome which is quite poor on the plugin front. But this one is available for Chrome and works pretty nice: