Lagrange point

A Lagrange point is a point in space where the gravitational forces of two larger bodies, for example stars or planets, and the centrifugal force of a third, smaller object at that point cancel each other out. This allows the third object, for example a starship, to assume a fixed position relative to the other two objects without any power consumption.

Within any star system, several such points exist.

The L5 Test Station, part of the NX Project, was presumably located at Earth's L5. 

When a Delta Rana warship virtually appeared out of nothing in the proximity of Delta Rana IV, Worf assumed that the ship was riding a Lagrange point behind Rana IV's farthest moon.