Opportunistic network does not rely on any pre-existing infrastructure and no assumption is made on the existence of a complete path between source and destination. The development of efficient routing protocols for opportunistic networks is generally a difficult task due to the absence of knowledge about the network topology. Therefore, routing is one of the most persuasive challenges of opportunistic networks. In this chapter, we give the general definition of context information and emphasize the role of context information to take forwarding decisions in opportunistic networks. We classify the main routing protocols proposed in the literature on the basis of context information of users they exploit. Specifically, we classify two main classes of routing protocols, corresponding to context-oblivious and context-aware protocols. Then, we further classify context-aware routing protocols into two subclasses, i.e., partially context-aware and fully context-aware protocols, based on the amount of context information they use for routing. We emphasize and describe only routing protocols of context-aware category and the detailed discussion about context-oblivious routing protocols is out of the scope of this chapter.