Prevention versus Detection

What is the difference, if any, between Intrusion Prevention System (IPS) and Intrusion Detection System (IDS). This question applies to all the types of securty software where their names differ only in the use of either 'detection' or 'prevention.' Examples of this are:

host-based intrusion detection system vs. host-based intrusion prevention system.

network intrusion detection system vs. network intrusion prevention system

 

Detection: Reports the intrusion and notifies the admin who take the decisions.
Prevention : Reports the intrusion and takes the necessary actions to stop the attack.

 

Let me clarify that in asking what the difference between prevention and detection is, I'm talking specifically about names of security programs, or types of security protection, that differ only on the usage of prevention or detection. I'm not talking about the general difference in meaning or implication between the two words.

Also, can anyone verify the definitions given by lucas? I ask because it seems that many of the programs that are labeled HIPS typically don't fall into the definition given by lucas. I mean don't some of the HIPS programs out there require the user to decide what to do with the suspicious process? Because if there are any such programs that are labeled HIPS yet require such user intervention, that means one of two things, either the definition given by lucas isn't accurate or the program(s) are simply mislabeled.

 

Whitepaper of IPS/IDS
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