Definition: Verb is a part of speech that describes an action, state of being, process, or condition. A verb is an essential element of a sentence which agrees with the sentence subject in person and number.
In Spanish, all verb infinitives (base forms of verbs) have an ending -ar, -er, or -ir.
Example: hablar (to speak), comer (to eat), vivir (to live).
Interesting fact: Verbs ending in -ar are most common in Spanish. In addition, all newly-formed words in the Spanish language must take on the ending -ar.
Verbs in Spanish are either regular or irregular. Regular verbs follow certain patterns when conjugated, whereas irregular verbs typically do not, and so their forms for different subject-tense combinations are harder to predict.
Definition: Conjugation refers to the change a verb undergoes to express information about a person, number, tense, voice, and mood.
In general, conjugation of Spanish verbs is accomplished by removing the ending from the infinitive and adding a new tense and subject-appropriate ending to the verb stem.
Example: by removing -ar from hablar, we get the verb stem habl- to which we can then add an ending.
Conjugation of regular verbs in Spanish is straightforward as the verb stem remains unchanged regardless of the tense or subject used: yo hablo (I speak), yo hablé (I spoke), tú hablas (you speak), tú hablaste (you spoke).
Note: Conjugation affects the word stress by shifting it from the last syllable in the infinitive form to the penultimate (second to last) syllable in conjugated form (unless specifically marked by an acute accent mark).
Spanish irregular verbs are more challenging to conjugate because the stem of irregular verbs may undergo changes depending on a subject and tense or may not be part of the conjugated verb at all.
Example: tener (to have) becomes tuve and ser (to be) becomes fui when conjugated for 1st Person Singular in Preterite.
There is no one simple rule to follow when conjugating irregular verbs as is the case with the regular ones. There are some rules concerning changes to the root that help you navigate the irregular verb world, but some verb conjugations do not follow any particular pattern, so it will take time and patience to acquire them.
Good to know: Almost all -ar verbs are regular (around 95% of them), -er verbs are mostly irregular (around 72% of them), and -ir verbs are mostly regular (around 75% of them).