An infinitive is the most basic form of a verb. In English infinitives have the word “to” in front of them (to talk). In Spanish, infinitives end in -AR, -ER, or -IR.
• The largest number of Spanish infinitives end in -ar: hablar, cantar, etc.
• To create the present tense of most of these verbs, drop the -ar from the stem: habl-, cant-, etc.
Like the -AR verbs, regular -ER and -IR verbs follow a similar pattern in the present tense.
• For -ER and -IR verbs, drop the -ER or -IR from the infinitive (comer, escribir, etc.) and add the appropriate endings. The endings are the same for -ER and -IR verbs except for in the nosotros and vosotros forms.
• Add the verb endings:
Keep in mind that vosotros is not used in Latin America, they use ustedes (3rd plural) instead.