Reported speech always has two clauses:

The reported clause, which is a dependent clause, contains the content of the speech being reported, while the main clause, which is the reporting clause, contains a reporting verb.

Unlike direct reported speech, which repeats the exact words of a speaker, the words in the reported clause of an indirect reported speech do not exactly match the words in direct speech. Look at this example:

Since the speaker changes in indirect speech, personal pronouns and possessive determiners have to change as well to reflect the shift in perspective. This change typically depends on the context, but the general rule of thumb is to change first-person singular and plural pronouns to third-person singular and plural and change second-person singular and plural either to first-person or third-person pronouns depending on the context. Third-person pronouns typically remain unchanged. Look at the examples:

Adverbs and adverbial phrases of place and time and demonstratives may also have to change in indirect speech since these forms are used to express a place or time relative to the original speaker and the person reporting the speech must change them to fit the time and place the speech is being reported.

The most common change from direct speech to indirect speech is the change of tense of the reported speech which involves moving back one tense. Pay attention to the examples:

In the table below, you can see common changes in verb tense in indirect speech:

Some modal verbs shift back in time and change tense in indirect speech.

To report statements in indirect speech, the main clause is linked to the reported clause using the word 'that'.
reporting clause (main clause) + reported clause (that-clause)

The reporting verb is usually used in the past tense. However, it can also be used in the present tense, for example when reporting a conversation in real time. In such cases, the verb in the reported clause does not need to backshift, because the reporting and the original speech happen at the same time.

When Yes/No questions and alternative questions are reported in indirect speech, the structure of the sentence would be as follows:
reporting clause + 'if'/'whether' + the reported clause
Keep in mind that the reported clause is in statement form, which means it follows the normal subject + verb + object word order instead of the inverted word order of questions and takes a full stop at the end instead of a question mark.

To report a wh-question in indirect speech, a reporting clause is followed by a reported clause introduced by an interrogative word (who, what, when, where, why, how). The reported clause is in statement form, not question form.

'Who,' 'whom' and 'what' can either be the subject or the object of the reported clause. For example:

Commands and requests are reported with verbs like tell, ask, order, etc. The shifts in pronouns and adverbs also apply here. However, the main verb of the reported imperative does not undergo backshift in indirect speech; rather, it changes from the base form of the verb to a to-infinitives. Another important change in the indirect reported imperative is that the subject of the direct imperative which is the implied "you" becomes the object of the reporting clause and needs to be explicitly stated. For example:

When turning a negative imperative into indirect reported speech, "not" is added before the to-infinitive.

Some verbs like suggest, recommend, advise, etc. can be used in indirect reported speech. Like imperatives, these forms usually use to-infinitives, but they can also use present participles. For example: