Anyone with 15 minutes of free time can edit their hosts file to block 99% of the ads that appear on web pages, for free.
This works on PCs, Macs, and Linux/Unix computers.
What’s a “hosts” file? It’s a file named “hosts”, and every normal computer sold to consumers has one.
A background on hosts files can be found here, on Wikipedia.
Hosts files also block domains that serve popups, inject trojans, and spread viruses. Basically, you can block any domain you want quickly and easily. To get a hosts file with more than 16000 blocked domains (yes, there are at least that many ad servers, spammers, trojaners, and nasty virus spreaders out there) , follow the directions given here, on MVPs.org.
MVPs.org are not a bunch of anarchist hackers, they are a group of Microsoft “Most Valuable Professionals” giving free computer advice. I like to point that out just to reinforce the point that editing your hosts file to block ads is not some bleeding edge tech head idea. It’s just a sensible thing to do.