Below you will find the definition of many
What is Malware?
a general, catch-all name given to computer software that is
designed to get onto a computer without the users permission
and either damage a system (an individual application,
functionality, or operating system), or send information, act
as an annoyance.
The term itself is still not very popularly known, "computer
virus" is usually used in its place. Viruses are only one form
of malware, however. Other forms of malware include worms,
trojans, spyware, adware and rootkits. These terms are
A lot of the time, malware may fall into more than one of these
categories. For example, an adware may also be a spyware. As
such, several types of removal tools may recognise the same
infection. Different vendors may call them different names
(though many keep standard names) so different tools
recognising different infections may not necessarily mean that
you have more than one infection.
What is a Virus?
A virus is the name given to one specific type of malware. A
virus is designed to infect your computer files by making
copies of itself in your system. It may spread from computer to
computer if two computers are networked in such a way as one
can read and write to the others files. Strictly speaking,
viruses are unable to spread themselves to another computer by
themselves without being transferred with a "host" infected
Viruses may designed to cause problems with your computer, send
information to the designer, or interfere with day to day
What is a Worm?
A worm is a program designed to use a computer network to send
copies of itself to other computers, usually without the users
knowledge or permission. While some worms have been designed to
change settings or behavior on the infected computer, all worms
are designed to cause issues for infected networks by spreading
quickly from machine to machine and consuming available
More dangerous worms can also install software on a users
computer (such as spam email servers), or change settings and
manipulate data on your system.
What is a Trojan?
A Trojan Horse (or simply just trojan) is a form of malware
that infects your computer by disguising itself as a harmless
file. Once the file is opened or run on your computer, the
trojan is able to infect the computer as intended.
Strictly speaking trojans don't copy themselves from computer
to computer, they rely on manipulating the user into believing
the file is harmless. However, other forms of malware may use
trojans or trojan techniques to copy themselves from computer
to computer, relying on the user to accept the file.
What is Spyware?
Spyware is software that installs itself on your computer
without your permission and interfere with your actions on your
computer. It can also be used to collect information about you,
for example what websites you visit, or even financial
information. Spyware can be used to change settings on your
computer, redirect your web browsing, and install other
software on your computer without your permission. It can be
used to allow entry to other forms of malware to your
Unlike viruses and worms, spyware does not usually
self-replicate. Instead, it is usually installed on a computer
by making the user think they are installing something else
(acting as a trojan), or by exploiting a weakness in the
operating system or an application. Sometimes spyware might
even be included with a legitimate application installer.
What is Adware?
Adware is any software that displays or downloads
advertisements while the software is in use. This may sometimes
be a conscious decision on the part of the application
developers in order to be able to generate revenue to continue
development of the application. Other times, it could be
installed by an application acting as another form of malware,
such as a trojan or spyware.
While there are applications designed to detect and remove
adware, since it is not always installed separately to an
application these applications may not always be able to remove
What is a Rootkit?
A rootkit is an form of malware that installs itself at a very
deep level of the operating system, and as such can prove
itself very difficult to remove. They are often designed to
take advantage of, or change the operation of fundamental
functions the operating systems provides. Rootkits can be used
to change the behaviour of an operating system, to allow other
forms of malware or other attackers access to the system, or to
perform the functions of other types of malware at a level that
is very difficult to detect.
Rootkits are not always designed to do bad, however, and some
security software can use rootkits or rootkit techniques to
hide themselves from forms of malware designed to remove