This book , consider the issue that fully cooperate in routing the packets from source to destination. The open structure, lack of existing infrastructure and in accessibility to trusted servers make traditional security methods and systems insufficient for WSN. When dealing with important and critical data, preventing, or detecting and repairing, data is prime factor. Much research on security of network/web has focused on external threats; once good security systems have been put in place, it becomes even more important to address the problem of internal threats. However, traditional cryptographic solution is useless against threats from internal compromised nodes. In this book, a trust based security solution by using fuzzy logic is explained to provide effective security decision for information protection, secure routing and other network activities. evaluation is deployed among network nodes using , secure routing protocol (trust based AODV) based on trust mechanism.