The subjunctive is a verbal mood used to express desire, doubt, evaluation, indirect command, and hypothesis. It does not assert facts, but presents what is said as unconfirmed or dependent on something else. In Spanish it usually appears in subordinate clauses introduced by que or other conjunctions. The key is that it marks the speaker's attitude, not just the tense.

The subjunctive appears most frequently in subordinate clauses that depend on a verb, a noun, or an adjective in the main clause. It is activated by the combination of meaning and structure, not just a single word. In many cases, a subject change is required to use que + subjunctive. It can also appear without que in fixed expressions and in certain connectors.

Desire is expressed with verbs such as querer, esperar, desear, or preferir followed by que + subjunctive. It is also expressed with ojalá + subjunctive, which functions as an exclamation. The typical structure is subject + verb of desire + que + subordinate clause in subjunctive. In first person singular, the desire often targets another person or a future uncertain event.

Doubt and negation of certainty usually take the subjunctive in the subordinate clause. Verbs like dudar, no creer, and no pensar indicate that the speaker does not present what is said as certain. By contrast, asserting belief or certainty usually uses the indicative. The difference is pragmatic: what matters is whether it's presented as a fact or as uncertain.

Expressions of valuation normally use es + adjective + que + subjunctive. Noun phrases of judgment use es + noun + que + subjuntivo. These structures do not assert a fact, but an opinion or evaluation. If the valuation refers to the speaker themselves without a subject change, in many cases an infinitive is used instead of que + subjunctive.

Indirect command appears with verbs such as pedir, ordenar, recomendar, or sugerir + que + subjunctive. It is not a direct imperative, but a request or instruction conveyed. The force of the command depends on the verb and context, but the grammatical structure keeps the subjunctive. It is also used with permitir or prohibir + que + subjunctive to authorize or veto actions.

Some temporal and conditional connectors may require the subjunctive when the action is future or not performed. With antes de que, a menos que, and para que, the subjunctive is normally used because the subordinate clause expresses purpose or an unmet condition. It can take the subjunctive when the action is future from the speaker's point of view. The key is whether the subordinate clause is seen as not performed or hypothetical.

The present subjunctive is used when the subordinate clause refers to the present or the future from the main clause. Its endings differ from the indicative and change according to the conjugation. In regular verbs, -ar forms take -e and -er/-ir take -a in the first and third person singular. There are many common irregulars that are memorized as base forms.

Some verbs are irregular in the present subjunctive because they change the stem or the full form. Ser, estar, ir, tener, and hacer are very common and tend to appear in the main uses of the subjunctive. Maintaining these forms helps communicate clearly in contexts of desire, doubt, and indirect command. It is recommended to learn the patterns because they repeat in many phrases.

The imperfect subjunctive is used when the main clause is in the past or in hypothetical constructions with if. It has two equivalent series: -ra and -se, though -ra is more common in conversation. It is formed from the third person plural of the preterite, removing -ron and adding -ra or -se. In hypotheses, it often appears with si + imperfect subjunctive and the main clause in the conditional.

Hypothesis is expressed with si + imperfect subjunctive in the subordinate clause and conditional in the main clause. This structure presents improbable or imaginary scenarios, not concrete plans. The past-hypothetical can also use the past perfect subjunctive for hypotheses about the past, with si + hubiera + participle. The choice of tense marks whether the hypothesis refers to present/future or to the past.