What Are Crackers?

Crackers are people who try to gain unauthorized access to computers. This is normally done through the use of a 'backdoor' program installed on your machine. A lot of crackers also try to gain access to resources through the use of password cracking software, which tries billions of passwords to find the correct one for accessing a computer.
What damage can a Hacker do?
This depends upon what backdoor program(s) are hiding on your PC. Different programs can do different amounts of damage. However, most 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. Hackers can see everything you are doing, and can access any file on your disk. Hackers can write new files, delete files, edit files, and do practically anything to a file that could be done to a file. A hacker could install several programs on to your system without your knowledge. Such programs could also be used to steal personal information such as passwords and credit card information