Tone is 'the attitude that is conveyed by the narrator of a story'. A reader can be persuaded by a writer's use of tone particularly if it matches the readers own 'feelings' on the subject.
For example in Mein Kampf Hitler used a very superior tone - which matched the sentiments of the general population of Germany at the time.
This book is about two teens who struggle with different things, and they eventually find each other and discover that some of the small things that happen can mean something to you more.