The past perfect places an action before another past action. It is used to order two moments already closed in the past: first one action and then another. The basic form is haber + participle: ya había comido, when you arrived, he had already left. In a sentence like 'When the movie started, we had already found a seat', finding the seat occurred before the movie started. In narratives, it clearly marks which event happened first when everything takes place in the past.

The singular auxiliary of this tense is formed with the imperfect of haber: había, habías, había. Each form goes in front of the main verb's participle. They are used like this: 'I had spoken', 'you had spoken', 'he, she, you had spoken'. The auxiliary does not change according to the main verb; it only changes person. To form a complete sentence, just join the form of haber with the corresponding participle, as in 'había visto', 'habías perdido', 'había vuelto'.

The plural forms of the auxiliary are habían hadíamos and habíais. They are combined with the participle for all plural persons: 'nosotros habíamos salido', 'vosotros habíais llegado', 'ellos habían comprado'. The auxiliary ending marks the person, and the participle stays the same for all. In written and spoken Spanish, these forms appear a lot in stories, memories and explanations of events anterior to another past moment.

Regular participles are formed in a fixed way. Verbs ending in -ar take -ado: hablar → hablado, comprar → comprado, llegar → llegado. Verbs ending in -er and -ir take -ido: comer → comido, beber → bebido, vivir → vivido, escribir → escrito does not follow this pattern and belongs to irregulars. In the past perfect, the participle does not agree with the subject nor change for number or gender: había hablado, habían comido.

Some verbs form irregular participles that are used very frequently in the past perfect. Among the most common are 'dicho' from decir, 'hecho' from hacer, 'escrito' from escribir, 'visto' from ver, 'puesto' from poner, and 'roto' from romper. Also appear 'abierto', 'cubierto', 'muerto', 'vuelto', 'resuelto' and 'impreso'. These forms replace the regular participle expected, which is why they are memorized as fixed forms: había dicho, habíamos hecho, habían puesto.

The complete structure is haber in the imperfect + participle. No other word is intercalated between the two elements. The forms are: 'había cantado', 'habías cantado', 'había cantado', 'habíamos cantado', 'habíais cantado', 'habían cantado'. The auxiliary provides the person, the tense, and the value of anteriority; the participle provides the lexical meaning of the main verb. In 'ya lo habíamos terminado', habíamos places the action before another past moment and terminado expresses the action itself.

In a story, the past perfect orders events with precision. It is used to indicate the action that happened first and the preterite or the imperfect to continue the narration. Thus, in 'I arrived late because the bus had already gone', the bus leaving happened before arriving late. In 'When I opened the door, they had already turned on the lights', turning on the lights is before opening the door. If you tell a series of past events, this tense helps separate the narrative background from what happened earlier.

It is also used to express that a result already existed before another point in the past. The focus is not only on the action, but on the state that that action left behind. Therefore we say 'when he arrived, he had already closed the store', 'they had already reserved all the tables' or 'I had lost the keys before leaving'. The closing, the reservation or the loss had already been done when the second past moment arrived.

The imperfect describes habits, circumstances, descriptions and ongoing actions in the past: 'I lived there', 'it was raining', 'I was hungry'. The past perfect adds temporal priority: an action or state had already been completed before another past moment. Compare 'When I was a child, I lived in Seville' with 'When I was a child, I had already lived in Seville with my grandparents for a year'; the first presents a background situation, the second marks that that experience occurred before another moment in the past. If you don't need to signal anteriority, the imperfect is enough; if you need to mark that something had already occurred, use past perfect.

The preterite presents finished acts that advance the narration: 'entered', 'arrived', 'I bought'. The past perfect places an action even further back: 'had already entered', 'had already arrived', 'had already bought'. In one sequence, the past perfect marks what happened before and the preterite marks what follows: 'When I arrived, they had already eaten and then we left'. If you read a story and see two past actions, the past perfect indicates which happened first; the preterite indicates what happens next within the tale.