Tricycle landing gear
Tricycle gear is a type of aircraft undercarriage (i.e. landing gear) that is arranged in the fashion of a tricycle, with a single one/two-wheeled front undercarriage (i.e. the nose gear) under the cockpit and two multi-wheeled main gears slightly aft of the center of gravity, usually just behind the wings. This is in contrast to the conventional landing gear (a.k.a. "taildragger") that is arranged with two front gears and one tail gear, more commonly seen in early aircraft but rare nowadays except among propeller-powered light aircraft and some amphibious aircraft.
Tricycle gears are the most ubiquitous undercarriage arrangements for modern aircraft due to the convenience of takeoff, landing and taxiing, especially among the heavier jet aircraft where the engines and wings (and thus the aircraft's center of mass) tend to be more rearwards than conventional gear aircraft and a tail-down flare is typically performed when landing.