This paper reviews the state of the art in overlapping community detection algorithms, quality measures, and benchmarks. A thorough comparison of different algorithms is provided. In addition to community level evaluation, we propose a novel framework for evaluating algorithms' ability to detect overlapping nodes, which helps to assess overdetection and underdetection. We conclude that SLPA, OSLOM, Game, and COPRA offer the best performance. A common feature observed by various algorithms in real-world networks is the relatively small fraction of overlapping nodes (typically less than 30%), each of which belongs to only 2 or 3 communities.