What is the hardware physically behind Tidal, Spotify, QoBuz?

Dear Late Night Audiogoners,

I'm calling into the show tonight because I was wondering something you may know about.  What the hardware (and software) look like that allow streaming services to operate. 

Are we talking massive server rooms?  

Is there a physical process involved in getting music into a format to store for streaming?  Do the record companies need to transfer a digital file to the service for streaming? 

-Curious in Chicago