Even though Node isn't a framework (it's a cross-platform, runtime environment), it is used a base for application development. However, over time, things are changed and improved, but that breaks some of the API functionality upon which some existing applications are already built around. Since these applications still run fine with a previous version, they are not likely to be constantly updated to work with later versions. Therefore, previous versions are still offered to maintain compatibility with applications that have already been developed. However, if you're starting work on a new Node application, then you are better off using the latest version.