The MacBook Pro is a line of Macintosh portable computers by Apple Inc. that were first introduced on January 2006 at the Macworld Expo. The MacBook Pro replaced the PowerBook G4 and was the second model to be announced in the Apple Intel transition (after the iMac). The MacBook Pro is positioned at the high end of the MacBook family.
There have been two designs for the MacBook Pro, both using aluminum. The first design was largely a carry-over from the PowerBook G4. The second "unibody" design is a more tapered design with most of the casing made from a single block of aluminum. There are currently three MacBook Pro models: 13", 15" and 17". http://en.wikipedia.org/wiki/MacBook_Pro#Unibody-construction_MacBook_Pro