The simple past tense is used to talk about actions that were completed in the past. It can be formed regularly by adding "-ed" to most verbs like "worked" or irregularly with verbs like "went." There are three forms: affirmative, negative using "did/did not," and interrogative using "did" before the subject. Regular verbs are conjugated by adding "-ed" while irregular verbs must be memorized without a clear pattern. The simple past is used for narrating past events or habits from a specific time in history.