One of the greatest dangers in cyberspace is the identity theft. It's when a person with the help of some programs illegally takes identity of a person. The purpose is often illegal too. The thief tries to get enough information so he could pretend on someone else and to use stolen credit cards account. It's dangerous because the thief commits crimes and the person might be arrested for nothing.
Such kind of “crimes†are often done with the help of spyware. As we all know, spyware is engineered to record private information so it's perfect for identity theft. The most confident information might be taken without users knowledge and used for illegal purposes. Even the software is often installed without any permission. Sometimes it's not dangerous but if the information that spyware records gets in the hands of an identity thief you might be in big trouble.
There are many spyware programs today that offers remote installation. Remote installation enables you to put a spyware program on computer but without physical access to the machine. This spyware is called a Trojan horse if it's illegal. But it's useful for user monitoring, specially for children monitoring. But often this software is used for stealing your private information.
And it's important to know that spyware is a danger for your identity and not adware which is often treated on the same level as spyware. Adware is for advertising purposes only and often even legal.
It's very important to read the End User License Agreement for any software before the installation and to find out what kind of program you have and what are purposes of program's maker.
So you have to enter private information to your PC carefully or using public terminals, that also might have spyware program that logs keystrokes of every user. Users of public computer systems must be very precautious. Using online shop services and entering credit card number might cause the theft of your identity.