A massive, circular ring with an inner track of 39 symbols representing star constellations, capable of sending people and objects hundreds of thousands of lightyears via an interstellar conduit called a "wormhole." The Stargate, constructed millenia ago by the Ancients, is made of the alien mineral naquadah and weighs about 64,000 pounds.
One side of the gate holds nine equally-spaced, V-shaped locking mechanisms, or "chevrons," capable of locking at least seven constellations in place via a freely-spinning inner track. The first six glyphs lock down a point in space, while the seventh represents the point of origin. When the seventh chevron locks, an unstable energy vortex emerges from the gate, incinerating everything in its wake. Once the vortex is gone and the event horizon is established, outbound travel may commence. Once objects have exited the other side, the Stargate has the capability of shutting itself off.

The Stargate network extends beyond our own galaxy, and includes many thousands of gates. Most gates are paired with a Dial-Home Device (D.H.D.), by which a user dials an address to another world. The S.G.C. does not have a D.H.D., and instead has rigged a computer system to access the gate's systems and dial addresses.

The Stargate is essentially an enormous superconductor, capable of harnessing power from a wide variety of energy sources, especially electricity. The inner track is a safety feature. When the gate has absorbed enough energy this track will unlock, allowing a manual dial in case something dire has occurred to the D.H.D.

I couldn’t care less (but one must keep up appearances, right?)

Stargate - it’s a great big world.

With a great big swirl that you step inside to another world.

We’re talking Stargate. It’s a crazy trip.

You can go quite far and you don’t need a car or even a ship.

There’s Colonel O’Neill and Carter and Daniel and Teal’c.

Look out for that Goa’uld.

A large round stone circle. Bunch of symbols, spins around... ya can't miss it.

A sci-fi movie that came out in 1994. Starred Kurt Russel and James Spader.

That big round thing, with water that stands up for itself.

It's kind of a ring thing, comes with a "dialer". You hit the symbols, it spins around, lights come on... kinda flushes sideways. See below for usage: