Today, rapidly changing technology has made every organization look for a security cover for their computer system or network. With the crucial role to play in securing the security of an organization, Intrusion detection and prevention systems (IDPS) have become an integral part of it.A breach in computer network or system may be due to many reasons such as malware, misuse of the system or unauthorized access to it, etc. Intrusion detection involves the process of monitoring the activities occurring in a computer network or system. The object behind this is to look for the activities that violate or attempt to violate such network or system. Besides this, it also involves reporting of such incidents to the security administrators.Intrusion detection and prevention systems (IDPS) are systems to identify incidents of intrusion and reporting them to security managers. And not only this, several IDPS can along with detecting such threats can also restrain them from succeeding. This, in other words, means that they can do both: identify threats and also stop them from succeeding. The other usage of IDPSs includes identifying existing problems with security policies, documenting existing threats and to put a stop on the violation of security policies.How do they differ from firewall:Both intrusion detection system (IDS) and a firewall are used to give security cover to a computer network and system but they do differ in their approach. Firewall only restricts intrusions that come from outside of a computer network, while an IDS looks for an intrusion both from inside and outside of a system.The use of IDPS:Monitoring of malicious activities: IDPS monitors the malicious activities that occur or are likely to occur in a computer network or system. They use various techniques to identify such occurrences such as reconfiguring a firewall, reporting of a flow of traffic that must have been already blocked.Documenting and managing existing threats: IDPSs detects and goes for threat management by codifying the threats. It also looks for frequency and features of such attacks in order to make out the appropriate measures to stop such attacks.Stopping the violation of security policies: Existence of IDPSs let individuals restrict themselves from intentionally violating the security policies of a computer system or network.The rapidly changing technology and a growing dependence on computer network and system demands an active consideration of protection of the same as without a security detection and prevention system they are open for an intrusion.