The definite past tense (-di / -dı / -du / -dü)
Turkish has two everyday past tenses, and they mean different things. Today: the definite or eyewitness past, formed with -di. Use it for events you witnessed, did yourself, or are stating as plain fact. Geldim = I came. Gördün = you saw. Oldu = it happened / it became. The next lesson covers the other past (-miş, for hearsay or inference). Today is the bread-and-butter past — the one you'll reach for most often.
How to form it — three pieces
Verb stem + the -d tense marker (with vowel harmony) + a person ending. The endings are different from the present tense — these are the personal endings specific to -di past. For gelmek (to come), the stem is gel-: geldim (I came), geldin (you came), geldi (he/she/it came), geldik (we came), geldiniz (you-pl came), geldiler (they came). Notice that the third-person singular has no ending — just stem + -di. Negative goes between stem and tense marker: gelmedim = I didn't come.
Vowel harmony — which vowel goes in -di
Four-way harmony, matched to the last vowel of the stem. Last vowel e or i → -di: geldim, bildim (I knew). Last vowel a or ı → -dı: baktım (I looked), aldım (I took). Last vowel o or u → -du: oldum (I became), buldum (I found). Last vowel ö or ü → -dü: gördüm (I saw), güldüm (I laughed). Pick the form that rhymes with the stem and you're right.
Hard-consonant rule — when -d becomes -t
If the verb stem ends in one of the eight 'hard' consonants — p, ç, t, k, f, h, s, ş — the -d softens into -t. The vowel harmony is unchanged. gitmek (to go) → stem git- → gittim (I went, not 'gitdim'). bakmak (to look) → baktım. içmek (to drink) → içtim. konuşmak (to speak) → konuştum. Mnemonic for the hard consonants: 'fıstıkçı şahap' — the consonants in that phrase are exactly the eight that trigger the change.
The full set of person endings
After the -di / -dı / -du / -dü (or -ti etc.) marker, attach: -m (I), -n (you), nothing (he/she/it), -k (we), -niz (you-pl, with vowel harmony as -niz / -nız / -nuz / -nüz), -ler / -lar (they). Walking through görmek (to see), stem gör-: gördüm, gördün, gördü, gördük, gördünüz, gördüler. Through almak (to take), stem al-: aldım, aldın, aldı, aldık, aldınız, aldılar.
Negation and questions
Negative: insert -me / -ma between stem and tense marker. gelmedim = I didn't come. görmedin = you didn't see. almadık = we didn't take. gitmediler = they didn't go. The -me / -ma itself harmonizes with the stem: e/i/ö/ü stems take -me; a/ı/o/u stems take -ma. Question: add mi (with harmony) as a separate word after the verb. Geldin mi? = did you come? Gördü mü? = did he see? Aldılar mı? = did they take?
When to use -di vs -miş
Use -di when you witnessed it, did it yourself, or are stating it as bare fact: Dün sinemaya gittim = I went to the cinema yesterday. Annem bir kek yaptı = my mom made a cake (I saw it). News and history default to -di: Atatürk 1881'de doğdu = Atatürk was born in 1881. The -miş form, in lesson 19, covers events you only heard about or are inferring after the fact. For now, default to -di for any past event you're sure of.
