Delay and Disruption Tolerant Networking (DTN) is one of the research areas within mobile networking that has grown the fastest over the past few years. A lot of work has been done and published about DTNs, and DTN research has gone from a small niche area to a hot topic in many major conferences, including Mobicom, Mobihoc, Sigcomm, and Infocom. Work in this area addresses networking in environments where some of the implied assumptions of traditional network protocols cannot be met. These characteristics of the networks can include very long propagation delays and frequent disruptions in network links (meaning that there may never even exist a fully connected end-to-end path). Frequently, node mobility must be used to move messages through the network, with opportunistic communication contacts eventually allowing messages to be delivered to their destination. Work in this area was initially begun to support interplanetary networking, but soon many terrestrial scenarios with similar characteristics were discovered. Such scenarios include communication in remote and rural areas and developing countries, vehicular communication, and sensor networks. The very long delays and the lack of end-to-end connectivity means that traditional protocols that require frequent end-to-end interaction become unfeasible and thus there is a need for new communication architecture and application paradigms. Sessions should be bundled and send in single messages whenever possible, and applications must be designed such that they do not leave the user waiting indefinitely for an answer that may take a long time to be delivered. In this tutorial we will give a background and motivation to the research area and show what the differences from traditional networks are. We will then provide an outline of the research that has been done in the area up to this point in different aspects of the system, as well as provide some case studies of real systems. Finally, future challenges for research in this area will be provided. We believe both practical implementation knowledge and deep understanding of the topics are important to give a tutorial. and both instructors have experience in both aspects, and thus, our tutorial would be highly beneficial to participants.