We present the spectrum of distributed garbage collection techniques. We first describe those reference counting-based techniques and compare them, in particular with respect to resilience to message failures. Reference counting-based techniques are acyclic since they are unable to collect cyclic data structures. We then describe a number of hybrid schemes improving over distributed reference counting algorithms in order to collect cyclic garbage. We then describe tracing-based techniques derived from uniprocessor tracing-based techniques. Finally, we discuss the pros and cons of each technique.