This is the sixth year that the Masters Series is being called the Masters 1000, with the addition of the number 1000 referring to the amount of ranking points which are won, since it began in 2009.
Tournaments
Note: Although the Monte Carlo Masters is billed as taking place in Monte Carlo, it is actually held in Roquebrune-Cap-Martin, a commune of France adjacent to Monaco.
References
2014 ATP World Tour Masters 1000 Wikipedia(Text) CC BY-SA