Doctor Who is a British science fiction television series that first aired in 1963. It follows the adventures of the Doctor, a Time Lord from the planet Gallifrey who travels through time and space in the TARDIS, a time machine that looks like a British police box on the outside. The Doctor often travels with companions, facing various alien species and historical figures while working to save civilizations and right wrongs. The show is known for its imaginative storytelling, iconic characters, and ability to regenerate the Doctor, allowing different actors to portray the character over the years. This unique feature has contributed to the show's longevity and popularity, making it a significant part of British pop culture.