What IS Literary Criticism?
Literary criticism is the study, analysis, evaluation or interpretation of literature. It can be about one work, an aspect of one work, multiple works by an author, multiple works by different authors, and more. Most literary criticism is published in scholarly journals or in books.
When searching for literary criticism, it's likely that you will come upon books and articles that can help you learn more about your author or work but aren't exactly considered criticsm:
Book reviews are usually created around the time that a work comes out and provide a general overview and evaluation of the work. Book reviews do not analyze a work, but are designed to let readers know if a book is worth reading.
Biographical works examine an author's life and will likely also discuss their work, but they don't specifically analyze the work. Some biographical works include criticism, but make sure that the author is really analyzing the work and not just mentioning it. If you are writing a paper that analyzes a work in the context of an author's life, biographical works can be quite useful.
Plot summaries provide a basic summary of a specific work without analyzing it.