Generally the term “Hacker” is someone who breaks into computer networks for the happiness he gets from the challenge of doint it or with some other intentions like stealing data for money or with political motivations. Hackers are classified to different types. Some of them are listed below.
White Hat: A White Hat hacker is a computer network security professional and has non-malicious intent whenever he breaks into security systems. A White Hat hacker has deep knowledge in Computer Networking, Network Protocols and System Administration (at least three or four Operating Systems and very good skills in Scripting and Programming). White Hat hacker has also good knowledge in hacking tools and know how to program hacking tools.
A White Hat hacker has the skills to break into networks but he uses his skills to protect organizations. A White Hat hacker can conduct vulnerability assessments and penetration tests are also known as an Ethical Hacker. Often White Hat hackers are employed by companies and organizations to check the vulnerabilities of their network and make sure that no hole is available in their network for an intruder.
Black Hat: A Black Hat hacker, also known as a cracker, is a computer professional with deep knowledge in Computer Networking, Network Protocols and System Administration (at least three or four Operating Systems and very good skills in Scripting and Programming). Black Hat hacker has also good knowledge in many hacking tools and know how to program hacking tools. A Black Hat hacker uses his skills for unethical reasons. A Black Hat hacker always has malicious intention for intruding a network. Example: To steal research data from a company, To steal money from credit cards, Hack Email Accounts etc.
Grey Hat: A Grey Hat hacker is someone who is between White Hat hacker and Black Hat hacker. Grey Hat normally do the hacking without the permissions from the administrators of the network he is hacking. But he will expose the network vulnerabilities to the network admins and offer a fix for the vulnerability for money.
Script Kiddie: A Script Kiddie is basically a hacker amateur who doesn’t has much knowledge to program tools to breaks into computer networks. He often use downloaded hacking tools from internet written by other hackers/security experts.
Hacktivist: A Hacktivist is a hacker with political intentions. The hacktivist has the same skills as that of a hacker and uses the same tools as the hacker. The primary intention of an hacktivist is to bring public attention to a political matter.
Phreaker: Phreaker is a telecom network hacker who hacks a telephone system illegally to make calls without paying for them.