Capital letters are useful signals for a reader. They have three main purposes: to let the reader know a sentence is beginning, to show important words in a title, and to signal proper names and official titles.
What does it mean to use capital letters?
Capital letters, also called upper-case letters, are larger than, and often formed differently from, lower-case letters. Capital letters are used at the beginning of a sentence or a proper name and may be used to show respect. Some examples are: “The dog barked,” Daniel, the Lord, and Queen Elizabeth.