A literary technique pioneered by James Joyce that narrates the thoughts of a character in a literary work. The most notable works employing stream of consciousness are Ulysses by James Joyce, both The Sound and the Fury and As I Lay Dying by William Faulkner.

Here is an example, taken from James Joyce's Ulysses:

The priest's grey nimbus in a niche where he dressed discreetly.
I will not sleep here tonight. Home also I cannot go.
A voice, sweetened and sustained, called to him from the sea.
Turning the curve he waved his hand. It called again. A sleek brown head, a
seal's, far out on the water, round.
Usurper.

Stream of consciousness is more common today than it once was, however it is employed more conservatively.