The omniscient third-person narrator is privy to all facts and events relating to the story and can convey all characters' thoughts and feelings to the reader.
The objective form limits the narrator's knowledge of the story to observable actions or events. The narrator has no knowledge of the characters' thoughts or feelings.
In third-person subjective the story is written in the voice of a narrator who is able to convey the thoughts and emotions of only the main character.
Limited form tells the story from the perspective of the focal character, including his or her thoughts and feelings, but is written in the voice of an outside narrator who is unable to convey events not perceived by that character.
A great deal of popular contemporary fiction is written in third-person, including "Lord of the Rings" and the Lemony Snicket books (omniscient) and the Harry Potter books (limited).