"World" need to be capitalized when:
1-It is the principal word in a sentence; for instance, "'World' ought to be promoted when it is the main word in a sentence."
2-It is important for a legitimate name; for instance, "The Second Great War," "Universe of Warcraft."
3-It is essential for the title of a book, article, part of a composed work.For example, "Carolyn Arndt Is First Person to Fly Solo around the World on a Hang-Glider," New York Times.
