ABSTRACT. In this work, the explanation is about how the computer’s containing valuable information is being unsecured and the techniques to make it secure. This technique contains information on the tools and skills a hacker uses to infiltrate computer systems and networks. This work proposes the study of hacking; as the cost of hacking attacks continues to rise, many of the businesses have been forced to increase spending on network security. However, hackers have also developed new skills and techniques that allow them to break more complex systems. Hacking involves compromising the security of networks, breaking the security of application software’s or creating malicious program such as viruses, threats, logic bombs, worms, etc[1]. This work describes the various techniques of hacking and cracking, also how they work. I proposed that the term "hacking and cracking" historically referred to constructive, clever technical work that was not necessarily related to computer systems. Today, however, hacking and hackers are most commonly associated with malicious programming attacks on the Internet and other networks