On Nov. 23, 1963, a black-and-white science fiction show with laughable special effects premiered on the BBC in Great Britain.

It was called "Doctor Who."

The latest season starts in the U.S. on March 30 on BBC America with "The Bells of Saint John." It will be available on iTunes the day after broadcast.

The show's appeal to adults and children has lasted, with one small hiatus, over five decades for a reason. It doesn't follow any real (scientific) logic, provides excitement - and at times, pathos - and has an ever-changing cast, including a space-time machine, the Tardis, whose interior is infinitely larger than its exterior, and is disguised as a (now-antique) British police box.

How has the show stayed alive for so long?

"The original subtitle being adventures in time and space," said executive producer Caroline Skinner, "that says it all for me. I think it encapsulates the spirit of him being a character who can literally grab his companion's hand and drag her into a historical period or the far reaches of outer space or anywhere, really."

The series died in 1989, had a one-shot movie in 1996, and was rebooted in 2005. Its popularity has exploded. BBC America's broadcast of the 2012 Christmas Special pulled in 2.5 million viewers. It won a 2013 Peabody award for "for evolving with technology and the times like nothing else in the known television universe."

One of the ways the show is kept fresh is through regeneration. Each time a new actor takes over the part, the character regenerates. The venerable William Hartnell became the impish Patrick Troughton in 1966. Eleven actors have had the label "The Doctor," the latest being Matt Smith.

Each "Doctor" has companions. In 1963, Hartnell traveled with his granddaughter, Susan. When it was revived, the ninth "Doctor" (Christopher Eccleston) traveled with Rose, played by Billie Piper.

Smith is one of the few "Doctors" to lose his companions, Amy and Rory Pond, to an enemy, the Weeping Angels.

He starts the new season meeting Clara, played by Jeanne-Louise Coleman, who was in two earlier episodes of the series. Executive Producer Steven Moffat says of Clara, "She's tough, she's fast and hard to impress."

Coleman says about her "Doctor," Matt Smith, "He's kind of got this unbelievable infectious energy, this work ethic, that kind (that) has him wandering around his flat for 3 hours after we've wrapped, going over his lines as Doctor."

The first episode introduces a new villain to London: the Spoonheads. "What the Doctor often does is grab hold of what is omnipresent in your life and turn it into a monster," Moffat said in a conference call.

The world of "Doctor Who" is far larger than just the television show. The stories have been told professionally on radio and in books.

Audio drama producers Big Finish is producing an original piece, "Doctor Who: The Light at the End," with five of the living "Doctors" - Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy and Paul McGann.

In November, the BBC in England will air "An Adventure in Space and Time," which dramatizes the making of the first "Doctor Who" in 1963.