What is Citizen: An American Lyric about?

Claudia Rankine's book Citizen: An American Lyric is in essence a collection of prose and poetry that tackles the current state of race relations in the United States and beyond. Ultimately, it poses two questions to readers: What is the definition of poetry in an artistic landscape where genres are simultaneously expanding their boundaries and becoming ever intertwined? And, what is the definition of a citizen in a society where the rules as they are written down are often incongruous with the rules as they are acted out? 
The first section of the work is structured as a series of prose poems, all bound together by a consistent second person voice: the recurring “you.” While at first glance it may seem as though this “you” is the author simply speaking to herself, Rankine actually interviewed 25 of her friends, both black and white, in order to collect material for her poems. As a result, this first section, along with several other sections that feature the recurring “you,” becomes a composite of racial and social experience focused on the idea of the micro-aggression. A micro-aggression is basically just a statement, action, or incident regarded as an instance of indirect, subtle, or unintentional discrimination against members of a marginalized group.
In the more essayistic sections of the book, Rankine really digs into the ways in which micro-aggressions, when repressed by their victims, build up over time, leading to reactions that are deemed insane or immature. She uses Serena Williams' outburst in regards to a series of bad calls against her by a white line judge during a tennis match as a primary example. Rankine also comments on a white-dominated society’s ability to erase the people of a race and culture through acts of violence and prejudice, such as in the case of Trayvon Martin, and thus really opens up the question of who gets to be a citizen in U.S. culture.