This book presents the most recent description of rubber reinforcement, focusing on the network-like structure formation of nanofiller in the rubber matrix under the presence of bound rubber. The resultant filler network is visualized by electron tomography applied to rubber. In the case of natural rubber, the self-reinforcement effect is uniquely functioning, and new template crystallization is suggested. Here, the crystallites are also believed to arrange themselves in a network-like manner. These results are of great use, particularly for engineers, in designing rubber reinforcement.