This article provides an in-depth analysis of the streaming encryption algorithms of the eSTREAM project. This analysis provides a detailed description of the project's purpose, its two main profiles (software and device-specific algorithms), and the selected algorithms. It also focuses on important issues such as algorithm security issues, device implementation challenges, and the impact of new cryptanalysis methods on algorithms. Algorithms selected within the eSTREAM project (Salsa20, Rabbit, Grain, etc.) and their properties, as well as their efficient operation in hardware and software, are detailed.