The inherent freedom in self-organized mobile ad-hoc networks (MANETs) introduces challenges for trust management; particularly when nodes do not have any prior knowledge of each other. Furthermore in MANETs, the nodes themselves should be responsible for their own security. We propose a novel approach for trust management in MANETs that is based on the nodes own responsibility of building their trust level and node level trust monitoring. The main contribution of this work is in the introduction of a Node-based Trust Management (NTM) scheme in MANET based on the assumption that individual nodes are themselves responsible for their own trust level. We explore and develop the mathematical framework of trust in NTM. We have defined a proposed metrics for nodes to establish and manage trust. We also have presented some new algorithms for trust formation in MANETs based on experience characteristics offered by nodes.