Perfect Tense (haben)

Take three steps. Conjugate haben in position two (ich habe, du hast, er hat), build the past participle, and put that participle at the very end of the sentence. For regular verbs the participle is ge- plus the stem plus -t: ge + spiel + t gives gespielt, as in Ich habe Fußball gespielt.

Regular (weak) verbs follow ge- plus stem plus -t: gemacht, gekauft, gelernt, gewohnt. Irregular (strong) verbs end in -en and often change their stem vowel: essen gives gegessen, trinken gives getrunken, schreiben gives geschrieben, nehmen gives genommen. The strong forms have to be memorised, so learn each verb with its participle.

Two groups. Verbs ending in -ieren drop it completely: studieren gives studiert, telefonieren gives telefoniert, reparieren gives repariert. Verbs with an inseparable prefix also drop it: besuchen gives besucht, verstehen gives verstanden, erzählen gives erzählt. In both cases the unstressed first syllable already carries what ge- would mark.

Use Perfekt for almost everything you say out loud about the past — it is the standard spoken past tense across most of Germany. Präteritum belongs mainly to written narrative, plus the everyday exceptions sein, haben and the modal verbs, where Germans say ich war, ich hatte and ich konnte rather than the Perfekt forms.

Move the conjugated form of haben to the front or keep it after the question word, and leave the participle at the end. So Was hast du gemacht? asks what did you do, and Hast du das Buch gelesen? asks whether you read the book. The participle never moves out of final position.