When should a period be used after a complete sentence?

A period should be used after a complete sentence in the following situations:

1. Declarative Sentences: A period is used after a declarative sentence, which makes a statement or expresses an opinion. For example: "I love to read books."

2. Imperative Sentences: A period is used after an imperative sentence, which gives a command or makes a request. For example: "Please close the door."

3. Exclamatory Sentences: A period is used after an exclamatory sentence, which expresses strong emotion or surprise. For example: "What a beautiful sunset!"

4. Indirect Questions: A period is used after an indirect question, which is a question embedded within a statement. For example: "She asked me if I had finished my homework."

5. Abbreviations: A period is used after abbreviations, which are shortened forms of words. For example: "Dr. Smith will see you now."

6. Initials: A period is used after initials, which are the first letters of a person's name. For example: "J. K. Rowling is the author of Harry Potter."

7. Ellipsis: A period is used in an ellipsis, which indicates the omission of words in a quotation or a pause in speech. For example: "The quote reads, 'To be or not to be...'"

It is important to note that a period should not be used after a question mark or an exclamation mark, as they already indicate the end of a sentence. Additionally, a period should not be used after a sentence fragment or a heading/title.