When do I use the imperfect and preterite tenses?

While both the imperfect and preterite tenses are used to refer to actions in the past, they are used under different circumstances. In general, the preterite tense is used when talking about completed actions in the past - actions whose beginning and end points are specified. This can include actions which took place as individual events, actions which took place as part of a series of events or even actions that were repeated a specific number of times. There are many phrases or words which signal the use of the preterite tense, in particular, time phrases such as 'anoche', 'ayer', 'el año pasado', 'hace dos años' etc. The imperfect tense on the other hand is generally used to refer to actions in the past with no specific end. These can be actions which are yet to be completed or refer to a general time period in the past. In addition, the imperfect tense can be used to talk about actions which were carried out habitually in the past, the age of a person in the past, time and dates in the past, states, conditions or characteristics in the past or even for actions which created the setting for other past events. Phrases/words used to trigger the imperfect tense include 'a menudo', 'siempre', 'cada día', 'rara vez', 'todas las semanas' etc