Spanish/Imperfect

The imperfect tense communicates:

continuing past events (translates English was/were __ing)
customary, habitual events in the past
planned future events

Verbs are conjugated to the imperfect by taking off the last two letters of the infinitive and replacing them with an ending based on -ía or -aba.

Conjugating regular verbs in the imperfect

This is probably the easiest verb tense to conjugate.

-AR verbs take on the -aba endings. Here is an example:

Bailar (to dance)

bailaba: I danced
bailabas: you danced
bailaba: he, she, it, you (formal) danced
bailábamos: we danced
bailabais: you danced
bailaban: they, you (plural, formal) danced

-IR and -ER verbs take on -ía endings. Examples:

Venir (to come)

venía: I came
venías: you came
venía: he, she, it, you came
veníamos: we came
veníais: you came
venían: they, you (formal) came

Comer (to eat)

comía: I ate
comías: you ate
comía: he, she, it, you ate
comíamos: we ate
comíais: you ate
comían: they, you (formal) ate

Irregular verbs

There are only three.

Ser (to be)

era: I was
eras: you were
era: he, she, it was, you were
éramos: we were
erais: you were
eran: they were

Notice the accent in the "nosotros" form of "ser" and "ir."

Ir (to go)

iba: I used to go
ibas: you used to go
iba: he, she, it, you used to go
íbamos: we used to go
ibais: you used to go
iban: they used to go

Ver (to see)

veía: I used to see
veías: you used to see
veía: he, she, it, you used to see
veíamos: we used to see
veíais: you used to see
veían: they used to see

That's it! Those are all the irregulars.