• We authenticate your game online when you install and launch it the first time.
  
• We'll re-authenticate when a player uses online features, downloads new content or a patch for their game.
  
• The new system means you don't have to play with the disc in your computer. And if you are like me, always losing discs, this will be a huge benefit.
  
• You'll still be able to install and play on multiple computers.
  
• You can play offline.
  

Via Kotaku