The basic form of a Turkish verb is the infinitive, which ends in -mek or -mak, depending on vowel harmony (A-Type).

• If the last vowel in the verb root is a front vowel (e, i, ö, ü), the infinitive suffix is -mek.
• If the last vowel in the verb root is a back vowel (a, ı, o, u), the infinitive suffix is -mak.

Examples of Infinitives:

• gelmek (to come) - root gel- (last vowel 'e' is front)
• yapmak (to do/make) - root yap- (last vowel 'a' is back)
• okumak (to read) - root oku- (last vowel 'u' is back)
• görmek (to see) - root gör- (last vowel 'ö' is front)

Verb Stem:

The verb stem is obtained by removing the infinitive suffix (-mek/-mak) from the infinitive form.

• gelmek → stem: gel-
• yapmak → stem: yap-
• almak (to take/buy) → stem: al-
• vermek (to give) → stem: ver-

This verb stem is the base to which tense, mood, aspect, and personal suffixes are added for conjugation.