Adware
Programs that secretly gather personal information through the Internet and relay it back to another computer, generally for advertising purposes. This is often accomplished by tracking information related to Internet browser usage or habits. Adware can be downloaded from websites (typically in shareware or freeware), email messages, and instant messengers. A user may unknowingly trigger adware by accepting an End User License Agreement from a software program linked to the adware.
Firewall
A firewall prevents computers on a network from communicating directly with external computer systems. A firewall typically consists of a computer that acts as a barrier through which all information passing between the networks and the external systems must travel. The firewall software analyzes information passing between the two and rejects it if it does not conform to pre-configured rules. A firewall is a program that can be downloaded from the Internet and which monitors connections to the internet. It looks at every piece of data zipping across Internet connection. The firewall protects computers from malicious attacks and from hackers.
Malware (Malaware)
Malaware is essentially a programme that is installed onto your computer (usually unknowingly) that does things that you are unaware of. For instance companies, like Microsoft or advertising agencies, put tracking cookies or data mining cookies on your system that will provide them information about your computing practices. Most of these are not dangerous but sometimes a more malicious one will take control of parts of your computer. For instance when you connect to the Internet it takes you to a website you haven't seen before, or you get pop up ads from dodgy places (often pornographic), or it tries to dial another phone number instead of your ISP. All of these are frustrating and can be prevented with a combination of a good antivirus programme, a firewall, and a programme to detect and eliminate malaware. A couple of free programmes that assist with malaware include AdAware and Spybot. The term was created by a combination of "malicious" and "software". Malware describes Viruses, Trojans, Backdoors, Spyware, Hacktools, Batch Viruses and Trojans, Internet Worms, IRC Worms, Java Scripts, Webserver Scripts, VBS Scripts, Virus Construction Kits, Denial of Service Tools (DoS), Distributed Denial of Service Tools (DDoS), Flooder, Keylogger, Nuker and Sniffer.
Spyware
Stand-alone programs that can secretly monitor system activity. These may detect passwords or other confidential information and transmit them to another computer. Spyware can be downloaded from websites (typically in shareware or freeware), email messages, and instant messengers. A user may unknowingly trigger spyware by accepting an End User License Agreement from a software program linked to the spyware.
Spyware
Despite its name, the term "spyware" doesn't refer to something used by undercover operatives, but rather by the advertising industry. In fact, spyware is also known as "adware." It refers to a category of software that, when installed on your computer, may send you pop-up ads, redirect your browser to certain web sites, or monitor the web sites that you visit. Some extreme, invasive versions of spyware may track exactly what keys you type.
Trojan Horse
Trojan Horses are impostors--files that claim to be something desirable but, in fact, are malicious. A very important distinction between Trojan horse programs and true viruses is that they do not replicate themselves. Trojans contain malicious code that when triggered cause loss, or even theft, of data. For a Trojan horse to spread, you must, invite these programs onto your computers--for example, by opening an email attachment or downloading and running a file from the Internet.
Virus
A program or code that replicates itself; that is, infects another program, boot sector, partition sector, or document that supports macros, by inserting itself or attaching itself to that medium. Most viruses only replicate, though, many do a large amount of damage as well.
Worm
A program that makes copies of itself; for example, from one disk drive to another, or by copying itself using email or another transport mechanism. The worm may do damage and compromise the security of the computer. It may arrive in the form of a joke program or software of some sort. Unstructured external threat An individual outside your organization who may be a threat. This person is technically unskilled or unsophisticated.