While there are no hard and fast rules to cover every possible situation, there are certain basic principles, and a substantial degree of uniformity nonetheless.
Proper names (such as Rama or Ayodhya) are
capitalized.
Derivatives of proper names (such as Indian from
India) are usually capitalized. But derivatives of proper names that have gained an independent meaning (such as india rubber or indian ink), words that are no longer identified with the source name, are not capitalized. This depends on the accepted usage of the word.
Common nouns in proper names (such as Ashokan Pillar, or Gateway of India) are capitalized. Whereas the common
noun used alone (such as pillar or gateway) is not capitalized.
Short forms of proper names (such as the Rann for the Rann of Kutch) are usually capitalized.
The plural form of a common noun that is usually capitalized (such as Manasarowar Lakes) is also capitalized.
Common noun as part of a reference (such as national
highway 8 or National Highway 8) may or may not be capitalized, depending on common practice and usage.
Definite article in proper place names (such as The Ambassador, The East Indies) is capitalized when used as part of an official name or title.
Names of organized bodies (such as Government Departments and International organizations), as well as their shortened names, are capitalized.
Members of organized bodies (such as Member of Parliament) are capitalized.
Names of countries and states (Nepal, Rajasthan) are capitalized only when they are used as proper names, or as part of proper names.
Names of geographical regions and localities (The Himalayas, The Bay of Bengal) are proper names and are therefore capitalized.
Names of calendar divisions (March, April) are capitalized.
Names of historic events, such as the names of holidays (Diwali, Dussehra) are capitalized.
Trade names and brand names (such as Neem) are capitalized.
Scientific names, the names of phylum / class / order / family and genus (Homo) are capitalized, while the name of a species (sapiens) is not.
Fanciful appellations, when used with or for a proper name (such as Third World), are capitalized.
Personifications (such as Time and Fate) are capitalized.
Religious terms and names denoting the Deity (such as Lord, God, the Almighty) are capitalized.
Titles of persons, whether they are civil, religious, military or professional titles (such as Master of Science) are all capitalized.
Titles of publications, documents, acts and laws (such as the Freedom of Information Act) are all capitalized.
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