distance traveled
Distance travelled is the total length of the path an object actually covers, no matter how much it twists, turns, or doubles back. It is what a car's odometer measures: every metre of road counts, even if you end up back in your own driveway. Distance answers: how much ground did the object cover in total?
Precisely, distance travelled is a scalar quantity (a single positive number with no direction) equal to the length of the whole path from start to finish. If the motion changes direction, you add up the lengths of each leg without any cancelling. This is what makes it differ from displacement: displacement subtracts (so opposite trips cancel), while distance always adds. Its SI unit is the metre (m), and it can never decrease as the trip goes on.
You meet distance whenever you care about the journey itself rather than the net change: fuel used, steps walked, wear on a tyre, the reading on a pedometer. A useful truth to hold onto is that distance travelled is always greater than or equal to the size of the displacement. They are equal only for motion that never reverses direction; the moment the object backtracks, distance pulls ahead.
A runner does one full lap of a 400 m track and stops where she started. Distance travelled = 400 m, but displacement = 0 m, because her final position equals her starting position.
A closed loop shows the split cleanly: big distance, zero displacement.
Distance travelled is a scalar and is always positive (or zero if nothing moves); it has no direction and no sign. Do not attach 'east' or a minus sign to it — those belong to displacement.