Reported speech, also known as indirect speech, is a way of reporting what someone else has said without quoting their exact words. It is commonly used in writing and conversation to summarize or convey information given by someone else. In reported speech, the verb tense and pronouns may change to reflect the perspective of the speaker reporting the information.

Indirect speech is often used to:

1. Share information: When we want to convey what someone else has said, we can use reported speech to summarize their message. This allows us to report conversations, interviews, or statements made by others.

2. Distance oneself from the original speaker: By using reported speech, we can create a sense of detachment from the original speaker's words or opinions. This can be useful when presenting an objective viewpoint or when expressing disagreement.

3. Preserve the flow of conversation: In certain situations, it may be more practical to summarize what someone said rather than quoting them verbatim. This helps to maintain the flow of conversation or written text.

Rules for converting direct speech to reported speech:

1. Changes in pronouns: The pronouns used in reported speech are often different from those used in direct speech. For example, "I" becomes "he" or "she," and "you" becomes "he" or "she" if the reported speech is about another person.

2. Changes in verb tense: The verb tense in reported speech is often shifted back in time, depending on the original speaker's words. For example, present simple becomes past simple, present continuous becomes past continuous, etc.

3. Changes in adverbs of time and place: Adverbs of time and place may need to be adjusted to reflect the reported speech. For example, "today" may become "that day" or "here" may become "there."

4. Changes in modal verbs: Modal verbs such as "can," "may," "must," etc., are often changed to their respective past forms in reported speech.

5. Changes in reporting verbs: Verbs such as "say," "tell," "ask," etc., are used to introduce reported speech. These reporting verbs may need to be modified to match the tense and context of the reported speech.

Overall, reported speech allows us to convey information and express what others have said in a summarized and indirect manner. By following the rules of converting direct speech to reported speech, we can accurately report conversations and statements while maintaining proper grammar and tense usage.