In The Sound and The Fury, Faulkner uses the stream of consciousness narrative mode common in the early 20th century. In addition to Faulkner, it was used by writers such as Virginia Wolf and James Joyce.
Stream of consciousness is characterized by referential writing rather than chronological writing. It seeks to literally replicate on the page the inner monologue humans constantly experience as they move through life. It is meant to show meaning through association through leaps in thought.
One example of this in The Sound and The Fury is Quentin's obsession with the memory of Caddy looking at him through a mirror. He can be thinking about anything else, his broken watch, the child on the street, buying the irons, and his mind will leap back to that mental image. This is a powerful technique using the "show don't tell" principal to show us that Quentin can not let go of that image. adf