Dynamic defenses interact directly with attackers. By dynamically intensifying attacker interactions, dynamic defenses confirm the attacker’s purpose, clarify the threat level of each attacker session, and pragmatically contain the attacker’s activities. Operating in real-time and individually with each attacker session, the interaction and containment can last as long as the attacker engages or until the attacker is removed from compromised systems. Also, dynamic defenses are virtual. Once the attack stops, the defense concludes—no wasted resources. In the end, malicious activity is prevented from reaching and harming targeted assets, without layers of static rules. To add color on dynamic defenses, two examples are described in this insight. The first is a cloud-based deception approach from Acalvio; and the second is a rule-less Web Application Firewall (WAF) by Threat X, also cloud-based.