Other Security Threats - 1

Adware:

Adware can possibly be quite harmless but sometimes it is there to spy.

Harmless Adware:Sometimes you are offered a free program to download on the understanding that the free version displays advertising. Often you can upgrade to the paid version and then you do not see advertising when you use the program.

But even relatively harmless adware is considered Malware if it offends our ideas of informed consent.
 For example, you are invited to download a handy toolbar for your browser: it is also a mechanism for serving advertising to your browser or desktop but this is not explained to you. So it seems that you are actually being tricked into installing something without being clearly informed about what it will do. More sneaky adware Adware can be also be delivered by stealth (e.g. by Trojan Horses or Viruses), install itself on your computer and feed you advertising without asking. Really bad adware can also be spyware.

Spyware:

'Spyware' refers to programs that run without asking and invade your privacy. Spyware can track the websites you visit, collecting and reporting the information to another party. This other party would usually be somebody very keen to send you more 'targeted' advertising that you did not ask for.

Very bad spyware is intent on identity theft, including attempts to discover personal information such as your credit card details and passwords. If there is adware or spyware on your PC you might find that it runs slowly or that you see a lot more 'pop-up' advertising when you use the internet. On the other hand, clever spyware can also hide, undetected, without causing these symptoms.

Real Rogues:

This is the kind of software that claims, for example, to be a spyware remover – but actually is spyware or adware .
Real Rogues like this are definitely malware.

Read Other Parts Of This Post :
Malware : Introduction, Virus, Worms, Trojan Horse
Other Security Threats : Part 1, Part 2, Innovative Ways To Fight Against Malware