Botnet is most widespread and occurs commonly in today s cyber attacks, resulting in serious threats to our network assets and organization s properties. Botnets are collections of compromised computers (Bots) which are remotely controlled by its originator (BotMaster) under a common Command-and-Control (C&C) infrastructure. They are used to distribute commands to the Bots for malicious activities such as distributed denial-of-service (DDoS) attacks, spam and phishing. Most of the existing Botnet detection approaches concentrate only on particular Botnet command and control (C&C) protocols (e.g.,IRC,HTTP) and structures (e.g., centralized), and can become ineffective as Botnets change their structure and C&C techniques. In this book at first we provide taxonomy of Botnets C&C channels and evaluate well-known protocols which are being used in each of them. Then we proposed a new general detection framework which currently focuses on P2P based and IRC based Botnets. This proposed framework is based on definition of Botnets. Botnet has been defined as a group of bots that perform similar communication and malicious activity patterns within the same Botnet.