Lagrangian Point
Definition
Parking spots in space where the gravity of two bodies plus orbital motion balance out — the James Webb telescope sits at the Sun–Earth L2 point.
Technical definition
Five equilibrium points (L1–L5) of the restricted three-body problem. L1, L2, L3 are unstable and need station-keeping; L4 and L5 are stable for small mass ratios.
Example
JWST orbits the Sun–Earth L2 point 1.5 million km from Earth — far enough to stay cold and dark, close enough to phone home.
Common confusion
Lagrangian points are not zero-gravity spots. Gravity is still strong there — the balance is between gravity and the rotating frame's centrifugal effect, and only L4/L5 are truly stable.