The Cardiff Rift is a fictional wormhole in the science fiction television series Doctor Who and Torchwood, one end of which is located in Cardiff Bay, Wales. The other end is apparently floating freely through spacetime, and matter and radiation can pass through the Rift, allowing extraterrestrial and extratemporal artifacts, and occasionally life-forms, to "wash up" in Cardiff. It is described as "Unpredictable and elusive, it’s a gateway for alien creatures, alien weapons, all manner of alien technology and time anomalies to enter our world" and the "flotsam and jetsam of the universe since the dawn of time."
The Rift has been featured in episodes of Doctor Who and is central to the spin-off series Torchwood, which is based around a branch of the Torchwood Institute created to monitor activity around the Rift. The Rift acts as a plot generator, providing a wide and potentially unlimited array of possible plots for the series, much like the Hellmouth in Buffy the Vampire Slayer and the Bajoran wormhole in Star Trek: Deep Space Nine.
Read more about Cardiff Rift: Attributes and Effects, Similar Anomalies, Reception