BASIC Rules of Capitalization
Using proper capitalization is one of the easiest ways to show that you are a professional writer. Here are a few simple rules to help you use capitals correctly.
Rule 1: I
Always capitalize the word “I.” Always!
Capitalize the first word of a sentence. Always!
Rule 3: Proper Nouns
Capitalize proper nouns. Those are the names of specific people, places or things.
Example of proper nouns: Google, George Washington, America, Microsoft
Common nouns do NOT get capitalized. Example of common nouns: the president, a country, a business
Rule 4 : Don’t use capitals for emphasis
Do not use capital letters simply for emphasis. Do not write in all capital letters. It is hard to read, and it makes you sound like you are screaming.
This is wrong: I am sending you an Important Message about our Meeting.
This is even more wrong: I AM SENDING YOU AN IMPORTANT MESSAGE.
These are the basic rules. If you are interested, there are more capitalization rules and an ungraded practice quiz here.