Removing the AR, ER and IR from the infinitive and you will have the stem or base. Some verbs have the regular endings but have a change occurred in the stem of the verb except nosotros/nosotras and vosotros/vosotras forms.
In Spanish, there are three categories of verbs. The category is determined by the last two letters of the infinitive:
| AR verbs | almorzar (to have luch) |
| ER verbs | poder (to be able) |
| IR verbs | dormir (to sleep) |
To conjugate a verb means to change the infinitive so that it agrees with the different possible subjects (the persons or things that we are talking about it).
These verbs below are regular in their endings but they also change in the stem. See examples:
The verb "almorzar" is typical AR verb with an o->ue stem change.
yo |
almuerzo |
I |
have lunch |
tú |
almuerzas |
you |
have lunch |
él, ella, usted |
almuerza |
he, she |
has lunch |
nosotros, nosotras |
almorzamos |
we |
have lunch |
vosotros, vosotras |
almorzáis |
you-all |
have lunch |
ellos, ellas, ustedes |
almuerzan |
they |
have lunch |
The verb "poder" is typical ER verb with an o->ue stem change.
yo |
puedo |
I |
am able |
tú |
puedes |
you |
are able |
él, ella, usted |
puede |
he, she |
is able |
nosotros, nosotras |
podemos |
we |
are able |
vosotros, vosotras |
podéis |
you-all |
are able |
ellos, ellas, ustedes |
pueden |
they |
are able |
The verb "dormir" is typical IR verb with an o->ue stem change.
yo |
duermo |
I |
sleep |
tú |
duermes |
you |
sleep |
él, ella, usted |
duerme |
he, she |
sleeps |
nosotros, nosotras |
dormimos |
we |
sleep |
vosotros, vosotras |
dormís |
you-all |
sleep |
ellos, ellas, ustedes |
duermen |
they |
sleep |