This is the Tardis, the Doctor's Ship. "Tardis" stands for Time and Relative Dimensions in Space. If you didn't know, it can travel through time, and travels by disappearing in once place, and reappearing somewhere else almost instantly.
This is the Tenth Doctor, played by David Tennant in the latest series of the show. The Doctor is a 900-year-old alien from the planet Gallifrey, the last of an ancient race called the Time Lords, who were all but killed off in the great Time War, which lasted only 13 years, but spanned 57 centuries.
Here is Rose and The Doctor standing outside the Tardis. The Tardis is in the form of a Police Box from the 1950s. The Tardis is supposed to blend in with the surroundings because when the Doctor first landed on Earth, the Tardis's chameleon unit broke, and it is stuck like that.
The Doctor's main tool is the Sonic Scredriver, which can open/lock any door, break ropes, and even unscrew screws. Legen has it that it was created on one of the doctor's long Space journeies, when he looked at a screwdriver and thought that it could be a little more sonic.
A hero such as the Doctor is bound to encounter many villans, and the most iconic of these are the Daleks, cruel, unemotional beings encased inside an invincible metal body. They are the complete opposite of the Doctor, cold and evil, and bring out the best qualities in him.