Effective data management in today’s competitive enterprise environment is an important issue. Data is information, and information is knowledge. Hence, fast and effective access to data is very important. Replication is one widely accepted phenomenon in distributed environments, where data is stored at more than one site for performance and reliability reasons. Applications and architectures of distributed computing have changed drastically during the last decade, and so have replication protocols. Different replication protocols may be suitable for different applications. In this chapter, we present a survey of replication algorithms for different distributed storage and content-management systems including distributed database-management systems, service-oriented data grids, peer-to-peer (P2P) systems, and storage area networks. We discuss the replication algorithms of more recent architectures, data grids and P2P systems, in detail. We briefly discuss replication in storage area networks and on the Internet.