The imperfect tense (el imperfecto de indicativo) is used for description in the past. Remember how the preterite is used to narrate simple completed actions? The imperfect is the opposite; it describes anything that’s not a simple completed action. For example:

• To state date, time, and age in the past.
  • Era el 23 de abril. Eran las 2:00 de la tarde. (It was April 23. It was 2 pm.)
  • Nos mudamos cuando yo tenía 11 años. (We moved when I was 11.)
• To describe what something was like at any point in the past or “set the stage” of a narration with background details. (TIP: if you would translate something as “was ____ing” in English, you need the imperfect in Spanish.)
  • Cristina era fuerte y trabajadora, y sabía hacer la barbacoa. (Cristina was strong and hardworking, and she knew how to make barbecue.)
  • Llovía cuando llegamos al restaurante. (It was raining when we got to the restaurant.)
• To describe simultaneous ongoing actions in the past with “mientras”.
  • Yo estudiaba mientras mis hermanos jugaban. (I studied while my siblings played.)
• To describe repeated or habitual actions in the past. (TIP: if you would translate something as “used to ____” in English, you need the imperfect in Spanish.)
  • Ellos hacían barbacoas cada semana. (They made barbecue every week.)
  • Mi familia siempre iba a ese restaurante. (My family always used to go to that restaurant.)