When should capitalization be used?

Capitalization serves several key purposes in writing, and one of the most fundamental rules is that it should be used at the beginning of a sentence. This convention helps indicate the start of a new thought or statement and provides clarity to the reader. It establishes a clear structure in written language, making it easier to follow the flow of ideas.

In contrast, while some of the other options may touch on aspects of capitalization, they do not align with the basic rules as clearly as the correct choice does. Not all nouns require capitalization; only proper nouns and specific instances such as titles and names need to be capitalized. Similarly, dialogue incorporates capitalization, but it's only the first word of the dialogue that is capitalized and not all dialogue. Common nouns do not receive capitalization unless they begin a sentence or are part of a title. Thus, the practice of capitalizing at the beginning of a sentence is a foundational rule in English grammar.