The Porsche 993 is the company's internal name for the version of the Porsche 911 model manufactured and sold between late 1993 and early 1998, replacing the 964. Its discontinuation marked the end of air-cooled Porsches.
Like previous and future generations of the Porsche 911, there were several variants of the car manufactured, varying in body style, drivetrains, and included equipment. The Porsche 993 was replaced by the Porsche 996.
The external design of the Porsche 993, penned by Englishman Toni Hatter, used the basic bodyshell architecture of the 964, but with changed external panels, with much more flared wheelarches and a smoother front and rear bumper design, an enlarged retractable rear wing, teardrop mirrors, but keeping the doors and roof panels.
Sources : http://en.wikipedia.org/wiki/Porsche_993