Computer security is the protection of computer systems, and the data stored on them, from unauthorized activity. Some people seek to disrupt computer systems, obtain confidential information stored on computers, or keep others from gaining access to systems or data. Computer security involves preventing such activity from occurring, and detecting and reacting to the activity when it does occur.
Computer security is important because much of modern life relies heavily on computers. For example, computer systems control airline traffic, national defense, and banking transactions. Computer databases store medical records, personal financial data, and military secrets.
Unauthorized computer activity may be performed by authorized users who exceed their access rights, or it may be carried out by outsiders who gain access. A common method of gaining unauthorized access is to steal the identity of an authorized user and thereby trick the system into allowing access.
Computer security specialists use a variety of means to guard against unauthorized activity. They often build security features into the designs of software (computer programs or instructions). They may issue patches (small pieces of program code) to fix security problems in software after it is released. Many computer systems require a user to enter a secret password to gain access. Such technologies as cryptography, antivirus software, and firewalls also are used to protect computer systems. Cryptography is the translation of data into a secret code that only authorized users can translate back into readable language. Antivirus software finds and eliminates viruses and other potentially destructive programs from a computer. Firewalls are electronic barriers designed to prevent outsiders from gaining access to a computer system.
Unauthorized activity on computer systems is impossible to fully prevent. Therefore, computer security specialists have devised technologies to detect such activity, react to it, and correct or minimize harm. These technologies include electronic logs of computer activity, data backup systems, intrusion detection systems, and forensic data analysis tools. Forensic data analysis is the scientific examination of computer data to gather evidence of computer crimes.
