Third-person omniscience is when the narrator knows all the thoughts, feelings, and actions of all the characters. A great example of this would be the story "A Good Man is Hard to Find" by Flannery O'Conner. This story revolves around an African American made up of grandmother, mother, father (Bailey), son (John Wesley), daughter (June Star). They decide to take a trip to Florida and during the trip Grandma suggests they visit an old house she remembers (which ended up being in Tennessee) and which was followed by an encounter with the "Misfit" (an escaped serial killer). The Misfit ends up killing them a couple at a time and the grandmother tries to talk to the Misfit and tries to convince him that he is a good man. The Misfit tells us his story and his thoughts on Jesus Christ; he ultimately reveals that he finds purpose in being "bad". The grandmother manages to scare the Misfit when she reaches out to grab him, as a result he shoots her. This POV was very effective for this story because it was able to explain both family histories and could reach depths that the characters/narrators could reach on their own (without complicating the story too much). Without the third person omniscient POV the story wouldn't fit and flow as well