This book is a truly classic and often-cited example of the Coming of Age novel. The whole deal with this genre is that it shows us the development of a character or set of characters through their experiences and thoughts. If you want to get all fancy schmancy and German, you could call it a Bildungsroman, which is just a highfalutin’ literary term for "Coming of Age Novel." However, it is actually useful to go into the German terminology, since they have an even more specific word for what Portrait of the Artist is – Künstlerroman. This term represents a specific subgenre of Bildungsroman, in which we see the development of an artist, not just any garden-variety young person. Anyway, enough of the German; Portrait also falls under Literary Fiction, mostly because Joyce was really up on himself and just knew that his books were very special and brilliant (he was infamous for making comments along these lines, particularly when it came to Ulysses).
Finally, it’s quite well known for being one of the first real Modernist novels. Joyce, along with Gertrude Stein, T.S. Eliot, and Ezra Pound, among others, was known for really getting the whole Modernism ball rolling, in response to the Realist style prevalent in the 19th century. In (very) short, the Modernist movement was concerned with creating works of art relevant to a rapidly changing world, in which institutions like religion, capitalism, and social order were thrown into question by new and confusing ideas (Evolution! Marxism! Revolution!), technologies, and world events like World War I (or in this case, the Irish nationalist cause). Here, we see Joyce take on this challenge by creating a character who has to maneuver past the hang-ups of his family, church, and country by forging ahead on his own.