For users on a T1 or broadband connection they may be little more than an annoyance. However, many home Internet users are still connecting through slower dial-up connections. At that speed the information you actually want can take forever to download to your screen. You certainly dont want to waste bandwidth downloading two or three other screens you didnt even request.
For computers that arent kept up to date with patches from the operating system and respective application vendors and computers that arent running current antivirus or firewall software these pop-up windows can also pose a security risk on some of those shadier sites.
By using malicious code hidden within the HTML that makes up the web page an attacker can wreak all sorts of havoc on an unprotected machine. Even something as simple as clicking on the X on the pop-up window to shut it down can actually lead to installing a Trojan, worm, or other malware. Of course, if you dont keep your machine patched and dont protect yourself with some sort of firewall and antivirus software its probably only a matter of time before you have much bigger issues.
You cant block these ads by turning off a feature or service in the operating system (like you can for Messenger Service spam) and you cant block the port at the firewall because they are normal port 80 web traffic like the sites you actually want to visit. Blocking the port would also cut you off from the rest of the World Wide Web.
Thankfully, there are a whole slew of tools and 3rd-party utilities to help you regain control over when and how pop-up or pop-under or any other ad appears on your screen. Current versions of Internet Explorer, Firefox or other browsers contain native functionality to block pop-up / under ads.
PanicWare, Inc. offers a free tool called Pop-Up Stopper Free Edition. The Free Edition works with Internet Explorer, Firefox (or other Mozilla browsers) and Netscape web browser software. It provides basic blocking of pop-up / under ads and you can get free updates as the marketers figure out new ways to bypass your blocking and get their ads on your screen. There are other versions including Pop-Up Stopper Professional which includes the ability to block Messenger Service spam and control cookies among other things.
The list of available products is long and growing fast as users struggle with how to handle the onslaught of pop-up ads and developers seek to capitalize on their frustration by releasing products to help the users deal with the invasion. You can try the Google Toolbar or Stop The Pop-Up. For a good list including links to download and buy some of these products you can check out Free Pop-Up Blocking Software
If you want to kill two birds with one stone and get more protection for your whole system while blocking pop-up ads check out a firewall. Current versions such as Trend Micro PC-Cillin Internet Security 2006 or ZoneAlarm Pro contain features to block pop-up / under ads as well as banner ads. They also contain other features to help protect your privacy while surfing the web which may help reduce the amount of spam email you receive. Of course, they also restrict or control traffic into and out of your computer like a firewall should.
Advertising on the Web is somewhat of a catch-22. The web sites- whether reputable and legitimate, or of a somewhat lower moral character- have to make money. Advertising is one of the key revenue generators for most sites. But, because web sites dont take commercial breaks they have to get your attention somehow. Nobody likes those little business reply cards that fall out of every other page of a magazine either- but they get your attention so they keep doing it. Marketers will always come up with new and more clever ways to get their message in front of you. You just need to try and keep up and take back some control over how and when you choose to view their message.