These programs are installed without our permission, either to record information about us, or to make money from us by plaguing our computers with advertisements. For this reason, adware is classified as one of the two spyware categories... the other being surveillance spyware.

Besides the surreptitious adware just mentioned, there is also adware that clearly gives us the choice to download it or not... I term this 'responsible' adware. Let's take a look at these two adware types...

1. Responsible Adware

Responsible adware is installed with our permission -- generally when we download a free software application, such as a game, music, screensaver, etc. The advertisements are displayed while the program is running, usually in a window of the product or by pop-ups or banners.

Responsible adware is considered an acceptable form of revenue generation for software developers, as a way of earning an income from their freeware. The developer will receive a commission for any advertise products bought, or, sometimes, for each click on the ad.

The benefit to the consumer is that the software is free... but there is a cost in terms of the nuisance value of the ads. And some programs may inundate the user with ads, whilst others are more discrete. The quality or type of ad also varies considerably with the freeware, ranging from useful software to adult sites.

Examples of responsible adware within freeware are the e-mail program, Eudora, and the Opera browser. The programs offer the choice of being purchased advert-free or in free, sponsored mode, with ads. The point is, these programs clearly state that the free version contains ads and when we stop using the program, the ads also stop running.

Just as important for those who are determined to guard privacy, this adware is benign, in that it doesn't track our habits or provide information about us to a third party -- unlike surveillance spyware.

If you want to download a freeware program but the product page doesn't display a statement as to whether ads accompany the product, then scan through the privacy clauses of the End User License Agreement (EULA). It may feel like a time waste, but you may well regret it later if you don't... if there are no clauses informing you about adware or reassuring you about your privacy, then if you download the program there's a good chance you'll have something worse than adware accompanying it.

2.Surreptitious Adware

It's unfortunate for all of us that responsible adware is in the minority. There is plenty of freeware containing adware that can be installed without our knowledge, or without notifying us that it will be used for gathering information about us.

Unfortunately, surreptitious adware can also arrive on our computers by other means. For instance, we can install a program by opening spam email or their attachments; certain websites use a 'drive-by download' technique, which installs the adware via our browser, if it has vulnerabilities. So, ensure you are up-to-date with browser patches, or consider a more secure browser, such as Firefox or Opera.

The distributor of this software is able to build a profile of our surfing habits and so download targeted ads that we're more likely to click on. Also, they are likely to sell on our information to spammers, who will then bombard our inbox with emails that can contain any type of malware, so putting our security at risk.

The adware program records our information when the ads displayed within the application are retrieved from a remote server on the Web. The application triggers the ads when we are connected and the server can log information, such as our IP (Internet Protocol) address and the websites we have visited.

If the surreptitious adware came with freeware, then we are highly likely to have provided our e-mail address to obtain the program. This means the distributor can now sell on our profile of who we are and what we like doing on the Web to other marketers or spammers. The result? Uninvited e-mails offering us products, subscriptions, services etc.

Some freeware may even have surveillance spyware, such as a keylogger, bundled with the product. This records any personal, financial and password details tapped into the keyboard, putting us at risk from intended identity theft.

3. Protection Against Surreptitious Adware

Protecting yourself from this form of spyware cannot be ensured by using a spyware and adware remover alone, as no one spyware adware remover program will remove all spyware. So, my advice is to install two commercial and any number of free spyware removers... aim for four to five programs in total, running one each day.

On top of your spyware removers, if you ensure you have a two-way firewall, an antivirus with effective Trojan blocking, plus up-to-date patches for your software, then you're on the way to having the most effective protection against adware and spyware in general.