Streaming

If you download a file from the internet, it will take some time before it is stored on you HD.
You have to wait until the download is completed before you can do anything with this file.
In case of streaming audio this is very inconvenient. Therefore they conjectured up another method. The download starts, as soon as a buffer is sufficiently filled, the music starts to play.
The assumption is that although internet is fully asynchronous, the buffer is big enough too compensated for the variations in the incoming stream.

As usual with internet technology, the user simply types a URL to connect to the server.
Whatever this server is running, where the music is located, etc. is completely transparent to the user.
That is the trick making internet possible.
As your home network is a TCP/IP based network, all this technology can be applied within your home network too.

Does this make sense?
One might argue that this is adding just another layer making everything more complex.
Nothing wrong with mapping a drive letter to a share on the NAS, simple and efficient.

But if you want to do multi room audio, would you like to have a PC in every room and configure them (or reconfigure them each time you change something on the NAS)?
If you go the media player way, it is a networked box using streaming technology.

Today you can display the pictures on your smart phone or your PC on your TV because your (new) TV is DLNA compliant.

I expect more and more new AV gear to be networked and adhering to the DLNA standard.

See To stream or not to stream