In the Spanish language, all verbs belong to one of three classifications or groups.
1. Verbs that end in -ar
2. Verbs that end in -er
3. Verbs that end in -ir
Spanish verbs, when they appear in their original form (infinitives), are made up of two parts: a stem and an ending.
In the verb amar, –am is its stem. –Ar is the ending.
Spanish verbs are considered regular if their stem does not change when they are conjugated.