When do I use the perfect and imperfect tenses in German?

In German, the perfect tense is used to describe completed actions in the past, whereas the imperfect tense is used to describe ongoing or repeated actions in the past.

The perfect tense is formed with the auxiliary verb “haben” or “sein” in the present tense, followed by the past participle of the main verb. For example:

Ich habe gestern Deutsch gelernt. (I learned German yesterday.)

Sie ist gestern nach Berlin gefahren. (She went to Berlin yesterday.)

The imperfect tense, also known as the simple past tense, is used to describe actions that took place repeatedly or over a longer period of time in the past. It is formed differently depending on the verb:

• For regular verbs, add the endings “-te” or “-ten” to the stem of the infinitive. For example:

Ich spielte gerne Tennis. (I used to play tennis.)

Wir wanderten oft in den Bergen. (We often hiked in the mountains.)

• For irregular verbs, the imperfect tense is formed using specific stem changes. For example:

Ich war gestern müde. (I was tired yesterday.)

Du hattest gestern Geburtstag. (You had your birthday yesterday.)

In summary, the perfect tense is used for completed actions in the past, while the imperfect tense is used for ongoing or repeated actions in the past.