The simple past tense is used to describe actions that were completed in the past. It is formed using the past tense of the main verb. Regular verbs form the past tense by adding "-ed" to the base verb, while irregular verbs have unique past tense forms. There are three key components to a simple past sentence: the subject, past tense verb, and complement. Questions in the simple past tense use the auxiliary "did" and are answered with either "yes, subject did" or "no, subject did not."