In grammatical terms, the word “perfect” means completed. The prefix im– means “not,” so imperfect means not completed. Thus, the imperfect tense is generally used in situations where the completion of the verb is not certain, or at least not the point of the sentence. The acronym WATERS will help you remember that the imperfect is generally used to express ongoing situations that sort of “flow on” and have no specific place in time. Each word that represents a letter in WATERS indicates a situation when an imperfect verb will be used. In the following examples, verbs in the imperfect are in bold.
Llovía.
It was raining.
Cuando tenía tres años, quería ser bombera.
When I was three, I wanted to be a firefighter.
Eran las cuatro.
It was four o'clock.
Estaba cansada.
I was tired.
Yo visitaba a mi abuela de vez en cuando.
I used to visit my grandmother from time to time.
El sol brillaba y la vista era bonita.
The sun was shining and the view was pretty.
Since the English language doesn't have a special tense to indicate repetitive or ongoing actions, there are a number of ways to get across this idea. The expression “used to …“ in front of a verb, or even using the word “would” in front of the verb can indicate repetitive actions. For example: “I used to study a lot” or “I would cry every day in kindergarten.” To show ongoing actions in English, the past progressive tense is often used: “I was studying …“ Don't try to translate these expressions literally into Spanish, just use the imperfect conjugation of the verb.