What are auxiliary verbs in Spanish?
First of all, "auxiliary verbs" are aka helping verbs. "An auxiliary verb is used with a main verb to help express the main verb's tense, mood, or voice." (1)
In Spanish, they are used to form compound tenses like the:
progressive tense --> estar [+ present participle]
perfect tense --> haber [+ past participle]
Here are some other verbs that are used this way...
tener que [+ infinitive]
poder [+ infinitive]
deber [+ infinitive]
Ejemplos:
Estoy escribiéndole una carta a mi amiga. (I am writing a letter to my friend.)
Yo estaba viendo la tele cuando sonó el teléfono. (I was watching TV when the phone rang.)
Como ya he dicho, no tengo tiempo para hacerlo. (As I have already said, I don't have time to do it.)
¿Tienes que irte tan pronto? (Do you have to leave so soon?)
Podemos cenar en mi casa el viernes. (We can have dinner at my house on Friday.)
No debo saltarme el café por la mañana. (I mustn't skip coffee in the morning.)
Take a look at the present perfect tense in the verse below...
"Porque un niño nos ha nacido,
un hijo nos ha sido dado,
y la soberanía reposará sobre sus hombros;
y se llamará su nombre
Admirable Consejero, Dios Poderoso,
Padre Eterno, Príncipe de Paz."
Isaías 9:6
"For to us a child is born,
to us a son is given;
and the government shall be upon his shoulder,
and his name shall be called
Wonderful Counselor, Mighty God,
Everlasting Father, Prince of Peace."
Isaiah 9:6
The perfect is formed with the present tense forms of haber (to have (auxiliary verb)) followed by the past participle (i.e. salido gone out), which is the same for all persons of the verb.
Porque un niño nos ha nacido --> For to us a child is born (has been born)
ha (haber) + nacido (past participle of "nacer")
nacer (to be born)
un hijo nos ha sido dado --> to us a son is given (has been given)
ha (haber) + sido (past participle of "ser") + dado (past participle of "dar")
ser (to be), dar (to give)
Sources:
(1) Grammar Monster: "What are auxiliary verbs?" https://www.grammar-monster.com/glossary/auxiliary_verbs.htm
(2) How to use auxiliary verbs in Spanish https://www.thoughtco.com/auxiliary-verb-in-spanish-3078319
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