Serif Font: Like Times and courier Are a more traditional and they have small details to them.
San Serif fonts: Like Ariel and Comic Sans these fonts are more informal and modern they are also known as friendly font's.
In this rocky poster the font used is Franklin Gothic Heavy. The title is placed at the font and it is big and bold and it catches your eye.
The font it self look very sharp and it has this masculine look about it which goes with the film so it goes with the theme of the film.