Regional jet

A Regional Jet is a Jet-Powered Airliner that mostly has fewer than 100 seats. They mostly operate short-haul flights.

A Sud Aviation Caravelle operated by Finnair
A Douglas DC-9 operated by Austrian Airlines
A BAC-One Eleven operated by British Airways
A Yak-40 operated by Air Lithuania
A BAE-146 operated by Brussels Airlines
A Boeing 737-100 operated by Lufthansa

The First Regional Jet was the Sud Aviation Caravelle built in 1959. Quickly many more came like the Douglas DC-9, BAC-One Eleven, Yakovlev Yak-40, Fokker F28 and BAE-146. Many of the early Boeing 737 models are also in this category.