The world premier of Guardians of the Galaxy was held on July 21, 2014, at the Dolby Theatre in Hollywood. This was an hugely anticipated film, and this meant the marketing of the film was meant to be very cleverly crafted. The film was released in cinemas in the United Kingdom on July 31, 2014 and the 1st of August in the United States.

https://www.youtube.com/watch?v=wN10QltBBtE 

 They produced a teaser trailer which makes it very clear that they are wanting to get the audience to really get excited for the film and  gradually, day by day get closer to seeing the film.

There were several teaser trailers before the actual full trailer, this meant the intrigue for the film was trailed for longer to create a big buzz.