Maintaining your packages and updating them is an important task, and if you are part of a development team, with people possibly even in different regions or countries, it becomes mandatory that everybody should be working with the same configuration at all times. If the project is very dynamic (meaning that packages will be added, removed, or updated frequently), npm can become a bit slow and also produce consistency or security problems; to address this situation, in 2016 Facebook released a new package manager, yarn. (See https://yarnpkg.com/en/.)

A key feature is that you can seamlessly replace npm with yarn, and just start using the latter, because it shares the same feature set (apart from some minor differences) while working in a faster, more reliable, and more secure way. For instance, yarn can manage downloads in parallel, and even work with cached packages, so it would even be possible to do some updates without a connection to the internet! 

Installation is quite simple, and a bit ironic. Use npm with npm install -g yarn, and from that moment on, you will be able to use yarn directly and forget npm. See https://yarnpkg.com/en/docs/install for more complete documentation on the installation process.