Spyware, on the other hand, is almost always software that is actually installed on your computer — without your knowledge, usually, to monitor and report on what you do. It may be for the purpose of giving you specific advertising. More often, it is designed to steal personal information such as user IDs and passwords or credit card numbers.
Adware is software that generates ads, especially popup ads, to interfere with your computing and Internet surfing experience. As most people use the term “adware,” and I agree with them, “adware” does not include software that displays unobtrusive ads with your conscious agreement (not buried deep in a license agreement or installed without your agreement) as a way to provide free software for you. Examples of this latter “non-adware” case are Eudora (email) and Opera (web browser), both of which give you the option to purchase versions without advertising and have ad-sponsored versions available as free alternatives.
Malware is a more generic term to mean any program that is designed to abuse your computer system or trust. Spyware and Adware are in this category, as are Browser Hijackers, Trojans, Viruses and Worms.
What are Browser Hijackers?
Browser Hijackers are programs that grab your web browser — especially the vulnerable Internet Explorer — and change your home page and maybe your search preferences to go to sites of their choice. Why do they do this? Money, pure and simple. They hope that you will click on the ads or links they show there. These folks are getting paid for almost every click that you make on their site.
What are Trojans?
Trojans are, very simply, programs that seem to be one thing but actually have a totally different, usually bad, effect. For example, you might install a free game — but, in addition to giving you the game, it also installs a spam-generating program on your computer. Of course, nothing says a trojan actually haa to do anything nice for you to begin with — it can just do the nasty stuff…
How do I get all these nasty critters?
Web surfing. Opening emails. Simple, easy, every-day activities that go with connecting to the Internet. One ubiquitous web browser, Internet Explorer, has a well-advertised feature called Active-X. Until the latest version of IE, released for Windows XP only, IE would automatically download and run Active-X programs from websites without even asking you if you wanted that to happen. Wow, it’s bad enough with children and grandchildren saying “yes” to anything, but here you didn’t even get a chance — and if you don’t have WinXP SP2, you still don’t have a chance.
Two very common email programs, Outlook and Outlook Express, use Internet Explorer to display any emails that are formatted in HTML, so you get all the security issues of I.E. along with any unique to the program. Of course, the programs default to sending in HTML also (cute “stationary” or fancy fonts) so you’re all set up.