WHAT IS IT IN ENGLISH?

If the perfect tense is the solid, one-time, did-it-and-now-it's-over tense, then the imperfect tense is the imprecise, wibbly-wobbly, timey-wimey tense. It happened in the past, sure, and it's probably over with now, but it happened either repeatedly or over an extended period of time, and probably other stuff happened during that time as well. In terms of wumbo, we can translate these verbs as "was wumboing" or "used to wumbo."

I was running.                             I used to run.
You were laughing.                   You used to laugh.
Timmy was belching.               Timmy used to belch.
We were eating the cat.           We used to eat the cat.
Sally was going to the store.    Sally used to go the store.

HOW DOES IT WORK IN LATIN?

The imperfect tense endings are very distinctive and recognizable, and are thankfully also pretty easy to conjugate. First, let's see the endings, and then we can see how to apply them.

First Conjugation
infinitive - re + imperfect ending

Second Conjugation
infinitive - re + imperfect ending

Third Conjugation (regular)
infinitive - re + imperfect ending

Third Conjugation (i-stem)
infinitive - re + ie + imperfect ending

Fourth Conjugation
infinitive - re + ie + imperfect ending