The imperfect tense is one of the two tenses used to describe the past tense form in Spanish. It is one of the most regular tenses used in Spanish. The imperfect tense is formed by adding the imperfect ending to the stem of the word. Words that end in –ar have "–aba" endings and verbs ending in -er or –ir have "–ia" endings.

There are three verbs that are irregular in the imperfect tense. They do not follow a pattern, so they must be remembered.
The verbs are ser,ir and ver.

1. The imperfect tense can be used to describe background actions of the past.
- Eran las ocho y media cuando llegamos a la casa. (It was eighty thirty when we arrived at home.)
- Cuando fuimos a nadar hacia calor. (When we went to swim it was hot.)
2. It can be used to describe to describe routine actions that occurred in the past.
- Cuando mi madre vivía en Guatemala, comía muchas tortillas. (When my mother lived in Guatemala she ate a lot of tortillas.)
- Siempre nos reíamos en la clase porque nos divertíamos juntos. (We always used to laugh in class because we would have fun together.)
3. It can describe circumstances of the past.
- Cuando yo era un niño no teníamos una television porque vivíamos mas simples. (When I was a child we didn’t have a television because we led a simple life.)
- En Argentina se comía mucha carne. (In Argentina a lot of beef was eaten. )
4. The imperfect tense also describes progressive past actions or actions that occurred repeatedly in the past without a reference to when they began or when they ended.
- Cuando vivía en casa lavaba trastes cada dia. (When I lived at home I washed dishes every day.)
- Mi sobrino iba al parque cada fin de semana cuando era chiquito. (My nephew went to the park every weekend when he was little.)