Opening sequence characteristics

What always occurs: 
-The title of the film.

-The name of the production company and contributors.

What often occurs/ frequently occurs:
-Establishes the location or setting (the establishing shot)
-The name of the actor/ actresses are mentioned in the credits.
-There is a theme song. E.G 007 films, Jaws.
-Snapshot of the ending or conclusion before it has happened. The story then follows what happened up to that event, or unravels the mystery. E.G Pulp Fiction 1994.

What only sometimes occurs:
-There is an animated or sketched beginning. E.G St Trinians 1954, Juno 2007.
-There is a written story introduction. E.G Star Wars.

A good opening will: 
-Entice the audience to continue watching.
-Go seamlessly into the film.
-Sets the premise for the film. E.G Animation often indicates a comedy. E.G National Lampoons Christmas Vacation 1989.