WHAT ARE FILM TRAILERS?

I investigated the trailer genre using Film Space's new resources. The 'theory' behind the genre is presented in posts below, as I research the ' what, why, who, how, where, when'.
WHAT ARE TRAILERS?
I first answered a questionnaire (below) then I watched the trailer for
King Arthur: Legend of the Sword several times.  





































The trailer is a very effective advertisement for the film, in my view. It clearly signaled the film's genre (historical fiction, with elements of fantasy sci-fi) and made the film seem very exciting as there were all the features of a big feature film with high-production values, such as extensive VFX, battles, quests, royal families and their enemies, romance and danger. The trailer outlined the broad narrative arc of the King Arthur legend, a story that I am very familiar with through novels such as T.H. White's The Sword in the Stone and Mallory, but with modern twists, without revealing the outcome, thereby retaining the elements of suspense, enigma and peril. 

The trailer contained all the institutional information that would help me see the film such as release date and the names of the stars / actors taking main parts. 
It also used persuasive tactics such as "From the director of Sherlock Holmes..." which is an example of pedigree and which would influence me favourably, as Guy Ritchie updated that classic text to appeal to modern audiences with his use of digital technology, unconventional editing and humour.
The trailer was not a shortened version of the film exactly although it contained a number of visually spectacular clips and fast-paced editing that took the audience through the film's narrative arc without revealing outcomes (spoilers). 
The trailer picked some of the most arresting and powerful moments of the narrative in order to make the film appear action-packed and compelling. Its musical soundtrack is orchestral, with percussion and strings driving forward the action and making the film sound gripping, tense and exciting. The few lines of dialogue anchor the visuals at key narrative moments.
It is an action film with several battle scenes, which would appeal to male audiences, but the trailer also acknowledged female audience's enjoyment of romance through scenes with a female love interest as well as family love.

I answered a questionnaire on GENRE CONVENTIONS by matching sentences then checked to see if I had got it right: