What does Roon do?

Google is our friend, get yourself a general understanding and more specific questions will form. 

Maz, Roon's website is pretty informative and should easily answer all your questions. 

I have read what is on Google and the Roon website as suggested and it appears to me, as my equipment is certainly not Roon ready, I would have to replace a considerable portion of my system to use Roon. Not going to happen and I guess I'll stick with streaming Spotify  or perhaps trialling Tidal without Roon.

I was having dropouts streaming tidal thru my network using my laptop to control it so I bought the nucleus and now have a music server with a pretty cool os that consolidates my music( took me some effort) and allows to choose between my music or tidal. Roon also brings up album covers, lyrics, history and recently I started playing around with their dsp to smooth out some lumps in the bass in my room. You can install roon in a pc or a dedicated server. I'm using a nucleus driving a hegel dac or sooloos with impressive results, being more of a flip phone type it took me more effort than it should have but the system locates your sources, called zones, has you name them and then select which zone or zones you want to control.