The simple past tense is used for past actions, reported speech and conditional sentences. The verb is always expressed in the past tense, such as I ate, he ate or they ate, instead of I eat, he eats or they eat. Questions include compound verbs, such as, "Did I eat?"
For past actions, words or expressions with a specific time are included in the sentence. One example is, "He came to California one year ago." Time that has passed can be years or even minutes, and is expressed with the simple past tense.
Reported speech is usually written in the past tense even when the speaker said something in the present tense. In direct speech, one would say, "Do you like sushi?" In reported speech, one would say, "She asked me if I liked sushi." One exception is if the statement describes something that continues to exist, such as, "She told me she doesn't like sushi." The tense remains present because the statement is still true.
Conditional sentences express a statement about something that could be true and utilize simple past tense. For example, one would say, "She would read if she had time." Another form of conditional sentences uses the simple past tense to express an untrue idea or an unlikely situation.