Literary criticism refers to using different ideas as "lenses" in order to discuss literature. Just like the physical structures that they were named after, these "lenses" allow the reader to have a different perspective of a literary work and/or to focus more closely on a different part of the work. The "lenses" used in this kind of work are known as critical theories, and there are too many for us to cover. The critical theories page lists the ones that will be a part of this unit.
In one way or another, literary criticism has been part of the reader's experience throughout history, as conversations about literature usually center around particular topics or themes. You can find a more formal exploration of the evolution of literary criticism on the history page. It is important to note that, in this case, criticism does not mean judgment--it means analysis, examination. While in some cases works of literary criticism might lead to judgment being passed on the literary work examined, that is not the goal of this kind of work!