The presence of modern hackers dates back to the 1950s until the present day. Hackers are an integral part of our age. Beveren's model of hacker development and Bandur's social learning theory explain how hackers correspond with each other. There is sometimes a certain amount of skepticism towards hackers because some of them participate in cybercrime. This is where the question of hacker ethics arises, where it is difficult to define a boundary. Likewise, there are often contrary opinions about hackers as someone who is for or against technology. Hackers are motivated by testing their own and the computer's limits. Although there are as many as thirteen types of hackers mentioned today, the most famous classification is into hackers innovators, white hats and black hats. Operation Sundevil is the most famous hacker action, and the Anonymus, group. Hackers often use malware or methods like phishing. There are also examples of practice where companies hire hackers because they are experts in computer security problems. One such person is Kevin Mitnick. In his books, he teaches how to prevent social engineering, for example by not giving away information. Furthermore, how to prevent hacker break-ins, for example with a firewall and how to stay more private on the computer and the Internet by encryption.