Loft gives you an idea of how far and how high the ball will go. Drivers are the least-lofted clubs (not counting putters), while wedges are the most-lofted. Driver lofts for most players run between 7.5 and 12.5 degrees. Clubs increase in loft through the set until reaching the lob wedge, which is usually lofted around 60 to 64 degrees.
Also see:
FAQ: Are there industry-wide standards for the lofts of golf clubs?

