Basic characteristic of wireless networks that makes it vulnerable to attacks is its broadcast nature. Attacks are of various types that effect confidentiality and integrity of wireless network and in this paper, the authors are discussing about Jamming attacks. Jamming can stop or disrupt wireless transmission. It is interference, noise or collision at the receiver end. Jamming may happen unintentionally by network load or intentionally in form of attack. No specific hardware is used for executing it, it can be easily implemented by listening to the open medium and broadcasting in the frequency band same as network. If it is executed successfully it gives significant advantages to the attacker at very low cost. That is the reason why it is effective.