  This review summarises the main properties of Young Massive Clusters (YMCs),
including their population properties, particularly focusing on extragalactic
cluster samples. We discuss potential biases and caveats that can affect the
construction of cluster samples and how incompleteness effects can result in
erroneous conclusions regarding the long term survival of clusters. In addition
to the luminosity, mass and age distributions of the clusters, we discuss the
size distribution and profile evolution of the clusters. We also briefly
discuss the stellar populations within YMCs. The final part of the review
focusses on the connections between YMCs and the ancient globular clusters,
whether or not they are related objects and how we can use what we know about
YMC formation and evolution to understand how GCs formed in the early universe
and how they relate to galaxy formation/evolution.
