Various approaches from different fields have been proposed to improve the security of computer system. One such approach is Intrusion detection system monitors computer system in real-time for activities indicating attempted or actual access by unauthorized users. To build an effective intrusion detection system many techniques are available which gathers and analyze information from different areas within a computer system or network and identify various security threats, including both intrusions anomaly i.e. attacks from outside the organization and misuse i.e. attacks from within the organization. Artificial Immune System (AIS) which is inspired by the robust and flexible nature of Human Immune System (HIS) can be incorporated in current Intrusion Detection Systems (IDS) thereby improving their efficiency and performance.