Holby City is a weekly BBC1 medical drama that first aired in January 1999.
The show is a spin off from A&E department series Casualty - set in the same hospital but respective characters very rarely encounter one another.
Like Casualty, Holby City is set in the fictional county of Wyvern purported to be near Bristol.
Outside scenes of the city are represented by Bristol but - unlike Casualty - Holby City is filmed in Hertfordshire. It is believed the Casualty set was not big enough to accommodate the operating theatre needed for Holby.
The show is broadcast every week, all year round, and each series contains 52 episodes.
Nearly 1000 episodes have been produced across 20 series, with stars of the show rumoured to be among the very highest paid actors at the BBC.
Co-creator Mal Young, a soap opera veteran, decided to cast heavily from actors who had already established their career, particularly in soaps.
Holby City’s original cast in the first episode boasted the acting likes of Phyllis Logan (now known for Downton Abbey, but then most recognised for playing Lady Jane in Lovejoy), Michael French (David Wicks in EastEnders), Lisa Faulkner (Brookside) and Angela Griffin (Fiona Middleton in Coronation Street).
Famous faces have continued to figure in Holby City, with Adrian Edmondson, Patsy Kensit, Jane Asher and Robert Powell cast in significant roles.
Guest stars have included Antonio Fargas, Leslie Phillips, Susannah York, Richard Briers, Eric Sykes, Sheridan Smith and Phil Jupitus.
Around 4 million viewers watch each episode, down from a peak in the fifth series. Since then, ratings have declined year on year. The first series averaged 9.27 millions viewers for each episode.
Holby City has been nominated for over 100 TV awards and won around ten, including a BAFTA for Best Continuing Drama.