Doctor Who is a British Sci-Fi TV Show produced and televised by BBC. it depicts the adventures of a time-traveling, humanoid (according to the Doctor, Humans look like Time Lords, not other way around.) alien known as the Doctor. He is a Time Lord, an ancient and very advanced extraterrestrial civilization from the planet of Gallifrey.
He usually travels around in his Time Machine and a Spacecraft known as the TARDIS, short for Time And Relative Dimensions In Space (Name given by Susan Foreman, the Doctor's granddaughter). This TARDIS was originally outdated and faulty, but the Doctor stole it from the factory, thus beginning his adventure. (TV: An Unearthly Child)
It originally can change into any shape that fits the environment, but during the First Doctor's run, the chameleon circuit got stuck to it's 1963 London Police Box shape, giving it's signature shape. (TV: The Cave of Skulls)
However, the most signature thing about the TARDIS is the fact that it's bigger on the inside. Created by Time Lord technology, the interior exists in different dimension from the exterior but connected, thus making it look like a spaceship fits inside of the small wooden box.
It is known to at least be a size of a planet. The Doctor seems to have a library, a pool, a closet, a garage, several rooms and much more inside his TARDIS. (TV: Journey to the Centre of the TARDIS)
It works through a power source called the Eye of Harmony, an exploding star in act of becoming a black hole, suspended in a permanent state of decay.
All Time Lords, including the Doctor, when life is at danger and their body is dying, goes through a process called Regeneration in order to escape Death and renew their body.
It causes a drastic physical and psychological change, as their cells regenerate. As a result, Time Lords often change their body, mass, height, and personality. (TV: Planet of the Spiders)
There was a rule where you can only regenerate 13 times, but it isn't certain if the rule will still be enforced on the Doctor now that the Time Lords are gone.
Until now, the Doctor went through 10 regeneration, thus making the current Doctor, the 11th. However, there are complications regarding his regeneration numbers as there are one regeneration of the Doctor that he forgot about, (TV: Name of the Doctor) and the half-regeneration that 10th Doctor went through.
The weak point about the regeneration is that, when attacked during it, the Time Lord fully dies and can't recover.
However, the regeneration is what caused so many actors to play this role, and thus continuing the show for 50 years with one main character.
As his adventure continues, the Doctor picks up certain people, mostly humans as his companion, bringing them along to show them the whole universe.
Most of the time it's human females, but sometimes he brings along others, like Human Males, a Cyborg, or sometimes even another Time Lord. He usually do not have any kind of romantic relationship with them, but they do become great friends as they travel and face the danger of the universe.
And of course, he meets enemies that will threaten Earth, the Universe, or even the reality itself. The Doctor refuses to use violence, and most of the time defeat them through his plans and schemes.
it's most famous villain is Daleks, a cyborg-mutant army that eventually caused the Doctor to kill all Time Lords.
Other notable villains are: Cybermen, Weeping Angels, The Master, and The Valeyard.
Where to Begin?
With 50 years of history, 11 Doctors, Over 30 Seasons, countless numbers of episodes and Audio Books, Novels and comics, it just might be hard Where to begin your journey to start watching Doctor Who. So I'm here to tell you where and how to begin, so you can enjoy Doctor Who as much as I do.
I say begin with New Season 1, with the 9th Doctor. Doctor Who was in hiatus for about a decade, and it started again in 2005, with Christopher Eccleston as the 9th Doctor.
As it was targeted for people who never watched Doctor Who before, stories and settings would be explained.
It's such a shame that Eccleston left only after One series, but he was brilliant, and it was the first time people were introduced to The Last Great Time War.
So yes, Begin with Ninth- I guess I can say that he was absolutely Fantastic.
Then you can move onto David Tennant's Tenth Doctor, and Matt Smith's Eleventh Doctor. Both actors did a brilliant job portraying the Doctor, and I recommend you watch both of them.
Tennant played the Tenth Doctor from Season 2 to Season 4, and Smith played the Eleventh Doctor from Series 5 to Series 7.
Series 8 will soon begin, with Peter Capaldi as Twelfth Doctor.
Now, most people just watch the NewWho, but if you're really interested and wish to watch OldWho, then so be it. However, Be Warned- even though I have watched most of it, it's still very old. It can be cheesy, costumes and effects are old. I watched it mostly for the plot.
Now, if you want to begin your journey, I suggest you start with the Third Doctor. His episodes were when it was shown in Color, and Pertwee was just a genius. First and Second Doctor are good too, but it was in Black and White, and also some episodes went missing.