The waltz originated in the folk dances of Bavaria and was introduced to English Ballrooms in the early 19th century. A very close dance hold was necessary as the original fast tempo or 'Viennese' waltz was comprised of a series of very fast turns.
Its funny to note that the dance was seen as terribly raunchy at the time, with the man's hand around the lady's waist and chest to chest contact.
As Waltz music evolved into slower tempos, so the 'Modern' and 'Continuity' styles of Waltz came into being.
The Modern Waltz has a sophisticated and dignified personality and is all about romance, elegance and class.
The dance is identifiable by its body sway, rise and fall and poise. Done well, the Waltz is a thing of beauty as dancers appear to float around the floor.
This dance requires a large floor to do it justice and can only be danced to music with a 3/4 time signature - this often means hunting down some classics as modern waltz music is rare.