NFS stands for network file system. It is used to share the files or directories between two Unix/Linux machines.
NFS supports for the homogeneous environment which means it shares files or directories between same kinds of operating systems.
Network file systems don't mean that the files are stored in the network, those are stored on the hard drive but those are shared among the network.
Every network based file system will be a disk based files system.
The following diagram shows the systems connected to the network.
Operating system NFS Version
|Operating system||NFS version|
|RHEL 7||NFS 4.1|