Let's break it down.

Literary: Having to do with literature.

Criticism: A serious commentary or evaluation.

Literary criticism: A serious commentary or evaluation of a work of literature; sometimes called "lit crit" for short.

While we're discussing what literary criticism is, let's review what literary criticism is not:

• Negative feedback. Don’t be fooled by the word "criticism." Criticism as it pertains to literature is a thorough analysis, not just a negative opinion.
• A summary. A summary of a literary work sometimes can help you understand the plot of the work, but summaries don't usually contain criticism. If you need criticism, avoid summaries.