The Boeing 777 family

The 777 was designed to fill the huge gap between the 767-300 and the 747-400.
Initially (in 1986), this project was dubbed "7J7" and was a three-engined stretch of the 767.
But, already in the earliest phase of development the "possible" customers, which were involved in the design process, all wanted a complete new plane.
The 777-family started its life with three members (with some years between their births: 777-200 in spring 1994, the 777-200ER in fall 1996 and the 777-300 followed one year later).
This now has risen to six, with the development of the 777LRs (77L & 77W). Whereby the 77L had a rather complicated birth, because the development phase was iced for nearly a year due to the lack of interest. The latest project is the 77F (first delivery in late 2008).
In early 2007 Boeing said, that if the A350 becomes a too great threat for the T7, further improvements for the T7 program is Top1 on their agenda, before going about a completely new planedesign. This could mean, that some features of the 787-program could be applied to the T7 for improving their overall economics and results in extending the 777's life.