They tried to represent events and social conditions as they actually are, without idealization. This form of literature believes in fidelity to actuality in its representation. Realism is about recreating life in literature. Realism arose as an opposing idea to Idealism and Nominalism. Idealism is the approach to literature of writing about everything in its ideal from.
Nominalism believes that ideas are only names and have no practical application.
Realism focused on the truthful treatment of the common, average, everyday life. Realism focuses on the immediate, the here and now, the specific actions and their verifiable consequences. Realists are concerned with the effect of the work on their reader and the reader's life. This is a pragmatic view. Pragmatism requires the reading of a work to have some verifiable outcome for the reader that will lead to a better life for the reader.