I've often been asked this question, so here's the answer

But your not going to like this answer, and I was dubious writing this, as it may appear that I'm trying to frighten you, I'm not trying to fighting you, I'm just trying to inform you, so you can make a informed choice,

Different spywear collects different information, i.e. a tracking cookie, will only track your movements on the web and possibly retrieve your computer name, and other open source information, and nothing more,

For me to try to explain what every single piece of spywear could actually do, on a individual case byI case basis, would take years, so I've merged the worst of it together, this is a worst case scenario, and should only be looked upon as that, and NOT , I repeat NOT what every piece of spyware is capable of

Not every single spywear program is capable of this

Tracking and reporting your movements over the web, past and present, i.e. sending off you're entire history, favorites, Internet history past and present including deleted files etc. etc. etc.

Rrecording information about every download you ever done, past and present, no matter how you've downloaded it, or what program you've used to download it

Retrieving your email address, and every email address you've ever correspondent with

Mapping your hard drive, and sending off a complete copy of its structure

Reading your program files

Reading how often you use specific program files

Reading how often you use your computer / keyboard / mouse

Recording every single key stroke you make

Recording every search term you've ever used past or present

Recording how often you've made purchases on the Internet

Using your computers hard drive, and processor for their own purposes

Although the list goes on, I'll stop here

Only a very limited amount of spywear, will ever go this far, but some companies will always consider profit over ethical behavior there driving force, "if you've clicked yes,and signed their agreement, you've asked for all this and more" kind of thing, and some companies, won't even bother with the agreement

While other companies, try to make everything as clear as possible, and only collect anonymous information, to Taylor and improve there products for your benefit, in the future

Its not all black and white

Q. why would somebody want to put spyware on my computer?

A. Money, its all about making money, information is valuable the more detailed the information the more valuable it is, from general information about users, what part of the screen they usually leave there mouse pointer, what colors they prefer, so somebody could stick a colored banner we're you normally leave your mouse pointer, etc. etc., to more detailed information, i.e. user 1976092 likes to buy James Bond D.V.D,s, here's there email address, and computer number, and if there running pop up advertising on there computer, I'm sure you can work the rest out for yourself, most companies will say they only collect information to improve services for their uses, most companies consider selling more products an improvement in their services,