What is a Computer Virus?
In simple terms, a computer virus is a computer program
which
has been
created with malicious intent rather than to benefit the user of the
computer. To understand why such a program is called a virus we need to
understand a bit about what a virus is in the biological sense.
In the world of cell biology, the program that encodes
the
functions of
the cell is contained in the strands of DNA. A virus is a rogue strand
of DNA
that uses the resources of the cell to carry out its nefarious deeds
and to
reproduce itself. Some viruses can splice themselves into the strands
of DNA
to accomplish these ends.
The computer virus does the same thing with a computer
program, hence the
name. The earliest computer viruses would splice bits of rogue software
instructions into the computer programs installed on a computer. When
that
program was run, the rogue instructions would be executed.
Today the term computer virus is loosely used to refer
to many
kinds of
malicious software spread from computer to computer, usually without
the
knowledge of the operators.
What are Anti Virus Programs?
The earliest antivirus programs simply scanned each file
on a
disk drive,
looking for telltale patterns indicating the presence of virus
instructions.
Modern antivirus programs are more proactive, attempting to block
viruses at
their points of entry to a computer: email attachments, file sharing
applications, and so forth. Some antivirus programs will scan every
program
every time it is loaded from the hard drive to memory, before it is
run. This
tends to catch more viruses, but it can make the computer system
exceptionally slow. Unless the computer system is in an environment
that is
at high risk of virus attacks we do not recommend such defense programs.
How we Rated the Antivirus Software
Most reviewers focus on the effectiveness of the
software in
detecting
viruses. We figure they all are pretty good at this, or they would not
be
here. All antivirus software is quite effective at stopping virus
attacks.
Antivirus software is tricky to review because it works
in the
background,
silently and unobtrusively. You are much more likely to notice all the
things
the software isn't supposed to do than the things that it is supposed
to do.
Things like slowing your PC down to a crawl, or preventing you from
installing new programs at every turn.
