Here's a chart from the back of my Italian dictionary comparing present tense and imperfect tense (with mandare, to send):
There's a bit of a variation in the 1st person plural form, but otherwise, the difference between the present tense form and the imperfect tense form is the "-av-" infix between the verb stem and the endings.
After I realized this, it made the imperfect tense much easier because I was already familiar with this structure from Latin. Here's a chart with the Latin verb forms for present and imperfect tenses (with laudare, to praise):
Where Italian inserts "-av-" to form the imperfect tense, Latin inserts "-ab-." (My Latin textbook says, "-ba-," but since there are As on both side of the B, I think it could be considered either way.) The first person singular form is a bit different, but this change between present tense and imperfect tense clearly demonstrates that Italian derived from Latin.
