Vectored thrust is actively directed
thrust from a
jet engine or
rocket motor. There are many ways to actually achieve this, from
ducted exhaust to
jet vanes or even
liquid injection. The most famous example in the Western world is on the
AV-8 Harrier jump-jet, which can vector its thrust far enough to achieve
VTOL capability, and even
fly backwards. The
Harrier uses
ducted exhaust - rather than a single
tailpipe, the
Pegasus engine in the
Harrier emits thrust through four ducts, two on either side of the airframe. The ducts are
vaned, and can be rotated by the
pilot to allow the
Harrier to perform its magic. Jet exhaust is also routed through several small
thruster nozzles around the edges of the airframe (wingtips, etc.) to control the aircraft's
attitude while in '
hovering' mode, or at speeds below that where the
control surfaces are operational.
Some other vehicles that rely on vectored thrust include the Space Shuttle in its Main Engines, the Orbital Maneuvering System, and on the Solid Rocket Boosters. Some ICBMs and SLBMs do as well. The Su-27 Flanker's vectored thrust system allows pilots to perform the fairly impressive (and risky) maneuver known as Pougachev's Cobra. Russia lost a Flanker at the Paris Air Show while it was attempting this - but the pilot lived, having ejected horizontally at 100 feet altitude. Russia makes damn good ejection seats.