Below is an overview of capitalization rules. If you are unsure whether a word should be capitalized, you can consult a dictionary.
You should always capitalize proper nouns and words formed from them; do not capitalize common nouns. The following are types of words that you should usually capitalize:
Months (January, February) and days of the week (Sunday, Monday) are also treated as proper nouns. Seasons and the numbers of the days of the months are not.
Also, names of school subjects (math, algebra, geology, psychology) are not capitalized, with the exception of the names of languages (French, English). Names of courses are capitalized (Algebra 201, Math 001).
You should capitalize titles of people when used as part of their proper name.
Professor Smith but not “the Professor”
District Attorney Rodriquez but not “the new District Attorney”
Capitalize the first, last, and all major words of titles and subtitles of works such as books, online documents, songs, articles. Major words can include nouns, verbs, pronouns, adverbs and adjectives, but do not capitalize minor words like articles, and prepositions, and coordinating conjunctions (and, or, the, in) with the only exception if one of these minor words come first or last in the title.
The Cat in the Hat (book title)
I Want to Hold Your Hand (song title)
Capitalize the first word of a sentence.
She went to the store to purchase a new computer.
Capitalize the first word of a quoted sentence but not a quoted phrase.
Professor Smith says we should study “chapters eight through twelve and the study notes.”