I frequently check my server log files, and I have recently discovered more and more so called Adware/Spyware plug-ins on several of my visitors..
(I don't know if any of you have it, I can only see the IP addresses)
First some definitions (My own...) Adware:
A lot of shareware and freeware comes with some kind of advertisements to keep it free, this is called Adware.
It could be banners or pop-ups etc...
This is in most cases legal, and a way for the programmer to keep the program free.
But sometimes this the programs includes codes 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 the worst part of the spyware has also been called Scumware
This can be programs/code that installs itself when you surf on unsafe websites (porn, cracking/hacking etc....), scripts in e-mails, or it can be hidden in programs you think are innocent (cool small programs sent to you by e-mail etc...)
Some of these scumware can open up your PC (creates backdoors) to hackers, others can install code that directs you to different sites, some creates pop-ups when you surf, or others (that I hate the most....) hijacks ads on websites (like mine) and when you click one of the ads you are redirected to other pages, or to the correct pages, but the author of the scumware gets the payment for any sale.
Ways to discover if you have any spyware or scumware on your computer are if your computer is a bit slower than usual, you get pop-ups when you are not visiting any websites, or on websites that usually don't have pop-ups, or you are suddenly redirected to other websites..
There are several other warning signs too..
Try to do a search for Adware, Spyware or Scumware on google.com if you want to find out more.
But the easiest way to remove/prevent spyware and scumware is to use a spyware removal tool..
I can recommend two great (and free) tools:
Ad-Aware from Lavasoft: http://www.lavasoft.de/default.shtml.en
It's easy to use and it finds and removes most adware and spyware, and its free for non-commercial purposes.
One other great tool is Spybot Search and Destroy: http://www.safer-networking.org/index.php?page=home
I have just installed this one, it looks very good too.
I think Ad-Aware is a bit easier to use, but you can install and use the both. (to be completely sure..)
But I have one warning when you use this kind of tools.
They can identify harmless "adware" that you have installed on your computer yourself.
One example is the Alexa toolbar (I use it myself).
It does track your surfing habits, and stores what sites you have visited etc..
But this is what it is supposed to do to be of any use.
Some cookies that the tools identifies as adware/spyware are also harmless.
One example here are cookies from commission junction.
They are an internet advertising company, I use them on this site.
They use anonymous user data to create and report the browsing, purchasing and/or lead form completion activities of anonymous users. Most Cookies are harmless, and you don't need to delete them.
If you haven't used any spyware/adware removal tools before, you should install one of these.
I think you may get a surprise the first time you use them!
Just my thoughts about Adware and Spyware.
Feel free to ask any questions, and I'll try to answer.
(and look at my post count.. Muhahahaha