This book concentrates on the message forwarding issues of real-world people-centric Delay Tolerant Networks (DTN), such as Pocket Switched Networks (PSN) and Vehicular Ad-hoc Networks (VANET), which are omnipresent, and hence pertinent to examine. These people-centric DTN often exhibit discernible network properties, which can be leveraged to develop efficient message forwarding schemes. This book analyzes the mobility traces of a large-scale public transport network and reveals some latent properties of the spatio-temportal graphs of the same. Next, it has been discussed how these properties of people-centric DTN can be leveraged to build efficient message forwarding schemes.