Proper
nouns should always be
capitalized, unless they are written in a particular way for effect. Good examples were given by Loki7: e.e. cummins (a poet) and k.d. lang (a musician/artist).
Proper nouns name specific people, places and items. For example: The Birds is a film made by the world-famous director, Alfred Hitchcock. Note that The Birds is capitalized because it refers to a specific film; director is not capitalized because it is not referring to a specific director, just the generic term "director"; and Alfred Hitchcock is capitalized because it refers to a specific human being.
Specific geographical areas are capitalized because they are proper nouns. The Pacific Ocean is a large ocean. Note that Pacific Ocean is capitalized while later on ocean is not.
Proper nouns include:
Geographical Names
Structures and Monuments
Names of Ships, Aircraft and Spacecraft
Organizations and Agencies
Business Names
Academic Institutions and Academic Courses
Historical Events and Eras
Religions and Religious Terms and Artifacts
Nationalities and their Languages
Trademarked Names
Titles of Works (Books, Films, Art)
Titles used before a proper name.
An example of this is:
Professor Jane Doe; not Jane Doe, professor of my history class.
Try to capitalize proper nouns in titles of your nodes. Dannye is one of the folks who digs through E2, correcting all the titles that are not properly capitalized. It is a tedious job to do.