I was recently asked--by someone who had never watched an episode of Doctor Who--where they should start with the series. If you didn't grow-up watching the show, you may never fully understand how much some people cherish it. On the other hand, it's never too late to get started.

Doctor Who began in 1963 as a British television show to educate children about history while they watched the adventures of a time traveller called "The Doctor" and his companions. The focus of the show quickly shifted to a more mature audience, blending humor, science fiction, adventure, and horror. (Millions of children still watch the show; peering cautiously from behind the sofa to see if the scary bit is over has become one of the universally shared experiences of British childhood.) As of 2009, Doctor Who is still in production.

The Doctor's time machine is called the TARDIS. It looks like a big blue police emergency telephone box, and is far larger on the inside than the outside. Though the Doctor looks human, he is a member of an alien race called the Time Lords. When a Time Lord dies, he is able to regenerate a new body. (This conceit explains why the Doctor has been played by ten different actors.) The Doctor almost always travels with one or more companions, who play Watson to the Doctor's Holmes.

Many episodes of Doctor Who have been produced since 1963. Some are better than others. If you ask ten fans which episodes are the best, you'll get ten different answers. However, in chronological order, here are ten very good episodes, which should give you a feel for the series:

UPDATE Since compiling this list, I found quite a good list of the of the top 25 Doctor Who episoces. It's worth a look, particularly because of the brief commentary attached to each recommended episode.