Literary conventions are things or ways of writing that are typical of certain genres and that readers or audiences know, recognise, and accept as ways to move the plot along. The typical plot of some romance novels is about a man and a woman who have to work through problems and misunderstandings before they can fall in love.
Standard characters are a part of both writing and acting. In Elizabethan drama, some examples are the heroine who dresses as a man, the hero’s friend, the hard-boiled detective, the strong, silent cowboy, the girl next door, the mysterious stranger who comes to town, the cruel stepmother, and the handsome prince.
In a mystery crime novel, one of the rules is that a body must show up in the first three chapters or sooner. As the story goes on, there are more murders. The author cleverly hides clues, and by the end of the book, the guilty are brought to justice thanks to the skills of the main character detective.