I am trying to extract road data to use to implement a shortest path routing algorithm like A* or Dijksktras, I have been using QGis to try and extract the road data from map but I am really not sure what data to extract as there is huge amounts of data data. Can anyone help me out ?

I am trying to extract road data to use to implement a shortest path routing algorithm like A* or Dijksktras, I have been using QGis to try and extract the road data from map but I am really not sure what data to extract as there is huge amounts of data