"coming of age"

what do you think is ment by the term "coming of age"?
how might you apply this to movies?

To me the term "coming of age" means when our younge protaganist experiences an life changing event which carrys them into adulthood. throught the film we can see how they change from making rash unthought out desictions to making the correct ones; they mature and become smarter and more adult. 
a film that shows this experience is teen romance "the space between us" which is about a boy called Gardner who is born on the planet Mars. Due to the difference in gravity strength when he comes to earth for the first time problems with is heart occour which threaten his life. nievely he ignors the risk and runs away because the want to find his inter planitary pen pall tulsa (who is a girl from earth) is too strong. after much perswation she agrees to help him hind his long lost father. through out the film they fall in love. it is obvious when watching this how gardener changes, at first he makes the rash desction to run away ignoring the advice given too him and then lator because he has matured he falls in love but regardless too his feelings he still comes back to mars to save his life.