What is Adware?
Adware or advertising-supported software is any software application in which advertisements are displayed while the program is running. These applications include additional code that displays the ads in pop-up windows or through a bar that appears on a computer screen. Adware helps recover programming development costs, and helps to hold down the price of the application for the user (even making it free of charge)�and, of course, it can give programmers a profit, which helps to motivate them to write, maintain, and upgrade valuable software.
Some adware is also shareware, in that users are given the option to pay for a "registered" or "licensed" copy, which typically does away with the advertisements.
Some adware programs have been criticized for occasionally including code that tracks a user's personal information and passes it on to third parties, without the user's authorization or knowledge. This practice has been dubbed spyware and has prompted an outcry from computer security and privacy advocates, including the Electronic Privacy Information Center  (http://www.epic.org). Other adware programs do not track a user's personal information.
A number of software applications are available to help computer users search for and modify adware programs to block the presentation of advertisements and to remove spyware modules. To avoid a backlash, as with the advertising industry in general, creators of adware must balance their attempts to generate revenue with users' desire to be left alone.
Examples of Shareware with Bundled Adware
Kazaa�Filesharing program, also contains spyware
iMesh�Filesharing program, also contains spyware
Most Common Adware
The most common adware currently found on the net as of August 2004 are:
Ways to Block Adware
The easiest and most reliable method for blocking unwanted ads is to install a worthy adware removal tool. Adware Report tests and reviews popular tools every month (click here for a side-by-side spyware removal chart).
Next, if you're already using an adware removal tool, you should ensure that you have the latest update. Adware companies are very active right now and are releasing new versions constantly. If your product is more than a week or two out of date, you likely have new adware installed on your computer.
The next method is a bit more advanced. It involves editing an important system file and also requires some technical know-how. If that's you, read on.
Blocking Adware with the Hosts file
Adware companies make their money by distributing thousands upon thousands of ads on the internet. It's a fair amount of work to put advertising on the net, so to do it with any kind of volume whatsoever, most companies rely on "Ad Servers". The adware on your computer usually pulls ads from these ad servers. If it doesn't find any, it won't work. So one technique for blocking adware is to block your computer from accessing the ad server. By doing so, you block adware companies from transferring their ads to your computer...!
Unfortunately, this is not a perfect solution. The Adware still exists on your computer, and so it will continue to consume memory, disk storage, and time. However, you won't be seeing those ads anymore, so if other methods don't work, this is a good failsafe.
Here's how it works. The hosts file on your computer contains a list of domain names (for example, www.doubleclick.com) and IP addresses. Normally, your browser will first check the hosts file to resolve a domain name. If it doesn't find it on the local list (99.9% of the time), it will then resolve it using something called DNS lookup. The trick here is to first figure out the domain name of the ad server you want to block, and then map it to your local computer. Because your computer doesn't have an ad server, the adware installed won't work!
How to block over 1,100 internet advertisers, step-by-step
Step 1: find your hosts file:
Windows 3.x, 95, 98, Me: windows\hosts
Windows NT, 2000, XP: WINNT\system32\drivers\etc\hosts
Macintosh: Mac System Folder or Preferences folder. (eg., Macintosh HD:System Folder:Preferences:Hosts)
Linux, Unix: /etc/hosts
Step 2: Backup your hosts file, just in case you make a mistake. If you can't access the internet after making changes to the host file, just restore the old version.
Step 3: Update your hosts file by pointing unwanted ad servers to your local machine. This is done by adding lines to your hosts file in the following format:
Here is a ready-made hosts list with over 1,100 advertisers. You can copy its contents into your hosts file and immediately start blocking advertisers!
Step 4: Try visiting the site of one of the entries in your hosts file. You should get a "page not found" error. If not, try rebooting your PC and then try again.
Other Adware Resources
The following links are valuable and provide further information about Adware:
Cexx.org - large list of Adware, spyware, and other parasites. Includes removal instructions for many of them. Large list, but doesn't appear to have been updated in awhile.
Introduction to Homepage hijacking programs, one of the leading sources of computer frustrations.
DoxDesk - another nice source of adware and spyware descriptions, along with common adware blocking instructions.
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