Irregular verbs can fall into two categories in the present indicative: irregular in the yo form, or irregular in all forms.
Irregular in the yo form
As in every language there will be verbs that do not seem to follow any of the rules. Irregular verbs are verbs that violate conjugation rules for one or more persons and do not fall into any of the stem-changing or spelling-changing categories. And unfortunately, these are usually the most useful and regularly used words in the language. The following words are irregular only in the yo form. They are regular in all other conjugations.
Irregular yo Conjugations
caber quepo to fit caer caigo to fall dar doy to give saber sé to know traer traigo to bring ver veo to see
The compounds of these verbs are also irregular in the yo form:
There are only four verbs irregular in all forms in the present tense, but they may be the four most useful and used verbs in Spanish.
Irregular Conjugations ser estar ir haber yo soy estoy voy he tú eres estás vas has usted, él, ella es está va ha nosotros somos estamos vamos hemos vosotros sois estáis vais habéis ustedes, ellos, ellas son están van han
