Are there guidelines for when to use UPPERCASE, Capitalize Each Word, or Only the first letter?

In general, you should capitalize the first word, all nouns, all verbs (even short ones, like is), all adjectives, and all proper nouns. That means you should lowercase articles, conjunctions, and prepositions—however, some style guides say to capitalize conjunctions and prepositions that are longer than five letters.

1. When should uppercase be used?
2. Do you capitalize the first letter of every word in title?

When should uppercase be used?

In English, a capital letter is used for the first word of a sentence and for all proper nouns (words that name a specific person, place, organization, or thing). In some cases, capitalization is also required for the first word in a quotation and the first word after a colon.

Do you capitalize the first letter of every word in title?

According to most style guides, nouns, pronouns, verbs, adjectives, and adverbs are capitalized in titles of books, articles, and songs. You'd also capitalize the first word and (according to most guides) the last word of a title, regardless of what part of speech they are.