Hackers can be classified into different categories such as white hat, black hat, and grey hat, based on their intent of hacking a system.
A White Hat Hacker is computer guy who perform Ethical Hacking. These are usually security professionals with knowledge of hacking and the Hacker toolset and who use this knowledge to locate security weaknesses and implement counter measures in the resources.
They are also known as an Ethical Hacker or a Penetration Tester. They focus on Securing and Protecting IT Systems.
A Black Hat Hacker is computer guy who performs Unethical Hacking. These are the Criminal Hackers or Crackers who use their skills and knowledge for illegal or malicious purposes. They break into or otherwise violate the system integrity of remote machines, with malicious intent.
These are also known as an Unethical Hacker or a Security Cracker. They focus on Security Cracking and Data stealing.
A Grey Hat Hacker is a Computer guy who sometimes acts legally, sometimes in good will, and sometimes not. They usually do not hack for personal gain or have malicious intentions, but may or may not occasionally commit crimes during the course of their technological exploits.
They are hybrid between White Hat and Black Hat Hackers.
Next and the most dangerous class of Hackers is Script kiddies, They are the new generation of users of computer who take advantage of the Hacker tools and documentation available for free on the Internet but don’t have any knowledge of what’s going on behind the scenes. They know just enough to cause you headaches but typically are very sloppy in their actions, leaving all sorts of digital fingerprints behind. Even though these guys are the teenage Hackers that you hear about in the news media, they need minimum skills to carry out their attacks.
Script Kiddies are the bunnies who use script and programs developed by others to attack computer systems and Networks. They get the least respect but are most annoying and dangerous and can cause big problems without actually knowing what they are doing.
Another type of Hackers are Hacktivists, who try to broadcast political or social messages through their work. A Hacktivist wants to raise public awareness of an issue. Examples of hacktivism are the Web sites that were defaced with the Jihad messages in the name of Terrorism.
There are Hackers who are called Cyber Terrorists, who attack government computers or public utility infrastructures, such as power stations and air-traffic-control towers. They crash critical systems or steal classified government information. While in a conflict with enemy countries some government start Cyber war via Internet.
Red hat hackers are again a blend of both black hat and white hat hackers. They are usually on the level of hacking government agencies, top-secret information hubs, and generally anything that falls under the category of sensitive information.
A blue hat hacker is someone outside computer security consulting firms who is used to bug-test a system prior to its launch. They look for loopholes that can be exploited and try to close these gaps. Microsoft also uses the term BlueHat to represent a series of security briefing events.
This is a social status among hackers, which is used to describe the most skilled. Newly discovered exploits will circulate among these hackers.
A neophyte, "noob", or "newbie" or "Green Hat Hacker" is someone who is new to hacking or phreaking and has almost no knowledge or experience of the workings of technology and hacking.