Direct speech repeats, or quotes, the exact words spoken. When we use direct speech in writing, we place the words spoken between quotation marks (" ") and there is no change in these words. We may be reporting something that's being said NOW (for example a telephone conversation), or telling someone later about a previous conversation.
For Example: David said, "I write with my left hand.”
When we express the speaker’s words in our own words without changing the meaning, it is known as the Indirect or Reported Speech.
For Example: She said (that) they believed in forgiveness.
REPORTING VERB IN THE PAST TENSE
a) Simple Present becomes Simple Past.
b) Present Continuous becomes Past Continuous
c) Present Perfect becomes Past Perfect
d) Simple Past becomes Past Perfect
REPORTING VERB IN THE PRESENT OR FUTURE TENSE
When we use present or future reporting verbs, the situation we are reporting has not changed, so there is no tense change.
If a statement expresses a universal truth, its tense remains unchanged.
Modals that have a 'past form' can be used for indirect speech back shifting.
In reporting questions, the Reported Speech is introduced by some verbs as asked, enquired, etc.
When the question is not introduced by an interrogative word, the reporting verb is followed by whether or if.
A Reporting Verb need not always be 'said' or 'told'. There are many other Reporting Verbs in English.
REPORTING COMMANDS AND REQUESTS
In reporting commands and requests, the Reported Speech is introduced by some verbs expressing command or request, and the imperative mood is changed into the Infinitive.
EXCLAMATIONS AND WISHES
In reporting exclamations and wishes, the Indirect Speech is introduced by some verb expressing exclamation or wish.