Here's a quick technical summary gleaned from Boeing's website:
The 777 is a medium to long-range passenger airliner designed and manufactured by Boeing. There are five models in service - the 777-200, 777-200ER (extended range), longer-range 777-200ER, 777-300, and longer-range 777-300. The standard 777-300 seats from 386 to 550 passengers (depending on the seating configuration installed by the operating airline), and has a maximum range of 5,960 nautical miles (11,030km). It is 242' long, 60' high, and has wingspan of 200'. The 777 is powered by two Pratt & Whitney engines, and has a maximum takeoff weight of 660,000lbs.
The 777 was the first airliner to be designed completely using software tools instead of mockup modeling. The aircraft is 9% carbon-fiber composite by weight (compared to about 3% for other Boeing jets,) and boasts a "fly-by-wire" digital control system. Its engines give it a 40% power advantage over its predecessor (the 767), without generating any additional noise. The first 777-200 flew in 1994; the first production aircraft entered service with United Airlines in 1995.