Definition
Painted yellow lines on airport pavement that mark the path aircraft follow when moving on the ground. A solid yellow centerline shows the route to follow along a taxiway, while edge lines and other markings define the limits of the usable taxi surface.
Plain English
The yellow lines painted on the ground at airports that show pilots where to drive their aircraft when taxiing.
Context Anchor
Seen on airport parking areas, ramps, and taxiways before takeoff, after landing, and anytime the airplane is moving on the ground.
Derivation
Taxi comes from taxicab, a vehicle hired to move people on the ground. Aviation adopted taxi to mean moving an aircraft on the ground under its own power, so taxi lines are the ground-movement guide lines for airplanes.
Why Pilots Care
Staying on the taxi lines keeps the aircraft on the paved surface and away from soft ground, obstacles, or other aircraft.
Intuition Check
Taxi lines are not tracks, and the airplane will not follow them by itself. They are visual guides; the pilot must steer the airplane and confirm the path is safe.
Example Sentence 1
After landing, the pilot exited the runway and followed the yellow taxi lines back to the ramp.
Example Sentence 2
Even at night the taxi lines remained visible under the taxi light and guided the airplane safely along the pavement.