The mechanism is simple but perfect: the actors who sing, the lyrics, has to do with what is happening to them and it works pretty well. Nothing to say, the Americans know how to do: they can invent good plot, develop scripts in clean, know how to create characters and choose the performers. And know how to choose the songs. What could be a talent to "friends" becomes a perfect television drama. With a series of cover really happy. As in 16 points (1st series) titled "House" focused on affected homes, which has as its centerpiece the cover of A house is not a home (Burt Bacharach) launched by Dionne Warwick and revived by countless other singers (Sarah Vaughan between jazz performers ) to the memorable voice of r & b Luther Vandross. Have a nice weekend.