the boeing 737 is a twin narrow-body airliner built by boeing. at first, boeing was making it to be a shorter, cheaper airliner than its 707 and 727. however, the 737 has become a family of many different models. the number of passengers it can carry ranges from 85 to 215. the 737 is the only narrow-body airliner that boeing is making. the only types of 737 that boeing is still making are the -700, -800 and -900er. a version of the 737 with larger engines, the 737 max, came into service in 2017 but was grounded between 2019 and 2021 as unsafe.