Hacking is an act of remotely penetrating computer systems to gain knowledge about the system.
What are "hackers"?
Technically, a hacker is someone who is enthusiastic about computer programming and everything relating to the technical workings of computers.
What are "crackers"?
Crackers are people who try to gain unauthorized access to computers. This is usually accomplished through the use of a 'backdoor' program installed on your machine. Many crackers also try to gain access to computer resources with password cracking software, which runs through billions of passwords to find the correct one.
What kind of damage can a hacker or cracker do?
This depends on what backdoor program(s) are hiding on your PC. Different programs can do different kinds of damage. Most backdoors, however, allow a hacker to smuggle another program onto your PC. This means that if a hacker can't do something using the backdoor program, he can easily put something else onto your computer that can. A hacker could install several programs on to your system without your knowledge. Such programs could be used to steal personal information such as passwords and credit card information. Hackers can see everything you are doing, and can access any file on your disk. Hackers can create, delete and edit files wherever they want.
Your computer uses input/output ports to exchange data with other computers.
A PC has 65535 ports. Some ports are used to browse the web, others to send email and others
for downloading information (FTP).
Some ports are unused.
Hackers can enter your computer through opened ports.
Generally, the first thing a hacker does is to scan your computer to identify opened ports.
In order to protect your system against these attacks, you should install a software firewall.
A firewall will close unused ports and monitor opened ports.
