Access to computer systems can be gained in many different ways. The simplest of these is direct access. Being the programmer, developer or specialist working with the system puts you in control of how the computer or network functions. Access can also be gained through a method called cracking. Cracking is a method of finding and using somebody else's username and password. In order to crack a password, "you can make a good guess, try out a number of combinations, look for the combination (password) written someplace nearby or one might try to find an alternate way into the system, a "back door"" (2). Scanning is another way to "crack" information. Scanning is "[using] a computer program that automatically generates a sequence of phone numbers, credit card numbers, passwords or the like to try against a system entry test"(2). There are ways around scanning, such as putting a limit of attempts one gets to enter the correct password in the system entry test would stop the program from trying over and over again. An additional way one might gain access in through piggybacking. Piggybacking is "getting into a secured area by slipping in right behind someone who is cleared for access [Piggybacking] can happen if the person using a terminal ahead of you did not log off properly, and her account is thus still active; you can go in"(2), basically it is using another person's access to as it were your own. The piggybacker then has access to all the past user's files and can be destructive if they choose and wipe out the account. .
There are many different types of computer crimes, but there are basically two main categories, crimes against computers and crimes using computers. "Crimes against computers are usually based on the destruction of hardware and software or the theft of computer technology."(2). Many people get mad at computers for many reasons. Computers are based on human input, thus computers make mistakes.