Third person omniscient is a method of storytelling in which the narrator knows the thoughts and feelings of all of the characters in the story, as opposed to third person limited, which adheres closely to one character's perspective.
Through third person omniscient, a writer may bring to life an entire world of characters. For instance, Anna Karenina is told from multiple points of view. Some sections are told from Anna's point of view: "All the same, he's a good man, truthful, kind and remarkable in his sphere," Anna said to herself, going back to her room, as if defending him before someone who was accusing him and saying that it was impossible to love him. "But why do his ears stick out so oddly? Did he have to have his hair cut?"
Exactly at midnight, when Anna was still sitting at her desk finishing a letter to Dolly, she heard the measured steps of slippered feet, and Alexei Alexandrovich, washed and combed, a book under his arm, came up to her. "It's time, it's time," he said with a special smile, and went into the bedroom.
"And what right did he have to look at him like that?" thought Anna, recalling how Vronsky and looked at Alexei Alexandrovich.
But many other points of view are given equal importance:
The house was big, old, and Levin, though he lived alone, heated and occupied all of it. He knew that it was even wrong and contrary to his new plans, but this house was a whole world for Levin. It was the world in which his father and mother had lived and died. They had lived a life which for Levin seemed the ideal of all perfection and which he dreamed of renewing with his wife, with his family.