Types of TV Drama

Soap Opera
A type of serial.  Multiple characters who carry a multitude of storylines.  They will appear, reappear and disappear at any given time.  No single storyline will dominate.
An example is Eastenders. The themes in Eastenders seem to be changing as different dillemmas keep arising, which keeps viewers drawn to the programme.  Some examples of different themes are death, sexuality, marriage, etc.

Serial
Often open-ended.  It will have a conclusion that draws the viewer for the same unique viewing experience for the next programme.  It may take the form of a soap opera, a miniseries, or a telenovela.
An example is Brideshead Revisited.

Partners
A series that links to another series.
An example is Casualty and Holby City because both are set in the same Holby General Hospital, Holby City is a spin-off of Casualty, and characters from both programmes occasionally cross over.  There is a common theme of healthcare/hospitality and death in both programmes because they want the portrayal of events in their hospital to be as realistic as possible.

Series
A longer and more extended format with a multiple group of programmes, with the same set of characters.
Doctor Who is a type of Series with each series having a certain amount of serials (episodes).  According to the Guiness Book of World Records it is the "most successful" science fiction series of all time.  As it is sci-fi there is a recurrent theme of imaginative creatures, usually, who disturb the equilibrium and the Doctor is expected to be the hero by creating a new equilibrium.

Single Drama
A longer and more extended format, this can often be up to a film length (hour and a half).
Royal Wedding was a 90-minute single drama for BBC Two.

Drama Trilogies
A three-part series.


How is a TV Drama an entertaining experience?
Dramas are reportrayals of reality, so the viewer can relate to the characters and situations, resulting in a close bond created between the viewer and them.  Therefore, the audience might have a psychological response to what happens to the characters, e.g. sympathy.  There may also be a visceral response if there seems to be a common or cliche situation.