How did the Doctor acquire his TARDIS?

The Doctor, the main character in the British science fiction television series Doctor Who, acquired his TARDIS (Time and Relative Dimension in Space) through unusual circumstances. According to the show's mythology, the Doctor is a member of an alien race known as Time Lords, who are able to travel through time and space in TARDISes. The Doctor stole his TARDIS from the Time Lords' home planet of Gallifrey, where they were grown rather than built. The TARDIS was a Type 40 model, which was considered obsolete and outdated at the time the Doctor stole it.

However, something went wrong during the theft, and the TARDIS ended up taking the Doctor to Earth, where it became stuck in the form of a 1960s British police box. The TARDIS is much larger on the inside than it appears from the outside, and is essentially a sentient being with a mind of its own, sometimes even taking the Doctor where he needs to go rather than where he wants to go.