Basic Rules for Capitalization
The function of capitalization is to give distinction and emphasis to words. Capitalizing the first word of a new sentence sets it apart and makes it clear that a new sentence has begun. Proper nouns are capitalized to signify their importance as official names of people, places or things.
In most cases of capitalization, only the first letter of a word is capitalized. Proper nouns are always capitalized, regardless of where they fall in a sentence or the punctuation that precedes them.