Capital letters are used to start sentences, proper nouns, and titles. They are also used for acronyms and abbreviations.

1. Starting Sentences: Every sentence should begin with a capital letter. For example, “I went to the store” is correct, while “i went to the store” is incorrect.

2. Proper Nouns: Capital letters are used for the names of specific people, places, and things. For example, “John” is a proper noun, while “boy” is a common noun. Similarly, “London” is a proper noun, while “city” is a common noun.

3. Titles: Capital letters are used for titles of books, movies, songs, and other works. For example, “Harry Potter and the Philosopher’s Stone” is a title with capital letters.

4. Acronyms and Abbreviations: Capital letters are used for acronyms and abbreviations. For example, “NASA” is an acronym for the National Aeronautics and Space Administration, and “Mr.” is an abbreviation for Mister.

It is important to use capital letters correctly to ensure clarity and proper grammar in writing.