Wikipedia
Tardisodes are mini-episodes of the television programme Doctor Who created to accompany the 2006 series of the programme. Made by Doctor Who producers BBC Wales, each Tardisode is approximately 60 seconds long and serves as an introduction to one of the actual 45-minute episodes. They were available on the BBC Doctor Who website free of charge, and on mobile phones by subscription. They were produced as an effort by the BBC to expand the reach of Doctor Who beyond the television series, and include footage not seen on television, and some back-story for the following episode. Their name is a portmanteau of the words TARDIS and "episode".
The first Tardisode, a prequel to " New Earth", was released by the BBC on 1 April 2006; it was promoted in the accompanying children's series Totally Doctor Who. New Tardisodes were released a week before each episode aired, directly after a new episode had finished airing on BBC 1. They were created by the same team that produced the interactive Doctor Who episode Attack of the Graske in 2005.
The Tardisodes were advertised on BBC 1. In the advert, the TARDIS is shown to be on an ice sheet. This imagery is similar to that used in the background of the homepage of the official Doctor Who website in the run-up to the start of Series 2. This advert was shown immediately after the transmission of many Series 2 episodes, coinciding with the release of the latest Tardisode for the next week's episode online and to mobile phones.
Downloads of the Tardisodes to mobile telephones were less popular than expected: around 40,000 downloads, averaging 3,000 per episode. Downloads to personal computers were much more common, with 2.6 million downloads. Iain Tweedale, new media editor for BBC Wales, suggested two reasons for the low number of telephone downloads: although the BBC provided the episodes free, most users had to pay a fee to their mobile network, and many telephones were not compatible with the broadcasts.
DVD producers 2|entertain did not include the Tardisodes on the series 2 DVD release.
In 2007, the BBC's annual report said of the Tardisodes that they "were not the hit we expected although they were popular on broadband", and this may be why they were discontinued after series 2.
No Tardisodes were produced for later series, although a similar series of prequels were released on the Doctor Who website to accompany selected episodes starting with series 6.