• In English, infinitive verbs are preceded by the word to, as in to speak, to read, or to write.
• In Spanish, infinitives are only one word and end in either -ar, -er, or -ir, as in hablar, leer, and escribir.

Verb Stems

Many verb tenses use a form of the infinitive as the stem to which verb conjugation endings are attached. In general, for regular verbs, you simply need to remove the infinitive ending (-ar, -er, or -ir) to find the stem, and then you can the add specific endings needed to give tense/subject information.

-Ar Verbs

Verbs that end in-ar are more common than -er and -ir verbs. There are also fewer irregular -ar verbs than -er or -ir verbs. Here are some examples of common -ar infinitives and their stems.

-Er Verbs

Verbs that end in -er are the second-largest group of infinitives in Spanish. Here are some examples of common -er infinitives and their stems.

-Ir Verbs

Verbs that end in -ir are the smallest group of Spanish infinitives. Here are some examples of common -ir infinitives and their stems.