I would add that not only is the guitar portable... It is idealy suited to accompanying the human voice singing. 

Sixty years later, here we are, from "How much is that doggy in the window" to "Day in the Life" and everything that followed... what a wonderous cultural journey those plucky Liverpuddling lads set us all loose on. "So let me introduce to the act you've know for all these years" ...  as the rest of modern music history...  It is all dirivitaive from "I want to hold your hand". 

Now back to the woodshed.