Drop the -ar, -er, or -ir from the infinitive to get the stem. Then add the ending. Future is the only one that adds to the full infinitive, not the stem.

Present

Preterite (completed past)

Imperfect (ongoing past, "used to")

Future (adds to full infinitive)

These five carry most conversational weight. Memorise the full grid.

Present

Preterite

ser and ir share the same preterite. Context tells you which one is meant.

Imperfect

Only three verbs are irregular in the imperfect: ser (era, eras, era, éramos, eran), ir (iba, ibas, iba, íbamos, iban), and ver (veía, veías, veía, veíamos, veían). Everything else is regular.

Future (irregular stems, regular endings)

Present tense yo form ends in -go. The other four pronouns follow regular rules (or stem changes for some).

Stem vowel changes in all forms except nosotros. Endings stay regular.

nosotros keeps the original vowel: queremos, podemos, pedimos, jugamos.

These verbs use a special preterite stem and a unique set of endings: -e, -iste, -o, -imos, -ieron. Critically, no accents on yo or él/ella.

hacer's él form is hizo (c → z to keep the soft sound). decir's ellos form is dijeron, not "dijieron".

The conditional means "would do X". Formation: take the full infinitive (or the irregular future stem) and add imperfect -ER/-IR endings.

Endings (all three types)

Irregular stems (same as future)

tener → tendr-ía · venir → vendr-ía · poner → pondr-ía · salir → saldr-ía · hacer → har-ía · decir → dir-ía · poder → podr-ía · saber → sabr-ía · querer → querr-ía

Past participle formation

-AR → -ado (hablar → hablado) · -ER/-IR → -ido (comer → comido, vivir → vivido)

Haber forms by tense

The 12 irregular past participles

Four command forms: tú affirmative, tú negative, usted (formal), ustedes (plural). The negative tú, usted, and ustedes forms all use subjunctive endings.

The 8 irregular tú affirmative commands

The subjunctive is the "non-reality" mood: doubts, wishes, emotions, hypotheticals. Formation trick: take the present yo form, drop the -o, then swap the vowel.

Endings

The 6 irregulars

Common triggers: "Quiero que...", "Es importante que...", "Dudo que...", "Ojalá que...".

The gerund is Spanish's "-ing" form. Its main real-world use: progressive tenses with estar, describing an action in motion right now / at that moment / in the future.

Regular formation

Irregular gerunds (memorise)

Progressive tense formula

Examples: estoy hablando (I am speaking) · estaba comiendo (I was eating) · estaré trabajando (I will be working).

The gerund itself never changes for person or number, only estar does. The gerund is not used as a noun in Spanish (unlike English "running is fun" — Spanish uses the infinitive: "correr es divertido").

The same little word does three unrelated jobs. The word after it tells you which.

lo + adjective + que means "how …": no sabes lo difícil que es (you don't know how hard it is).

Fixed phrases worth memorising: a lo mejor (maybe), por lo menos (at least), lo siento (I'm sorry).

Spanish forces two contractions. They are never written out in full.

voy al mercado (to the market) · la puerta del café (of the café). Only with the article el, never the pronoun él: se lo di a él stays separate.

al + infinitive = "upon / when doing"

A tidy replacement for "cuando + verb": al llegar (on arriving) · al verlo (on seeing it) · al amanecer (at dawn, as day broke).

para looks forward to a goal; por looks back at a cause or moves through something.

Quick test: if you can say "in order to", use para. If it's "because of / by / through / in exchange for", use por.

ser = what something fundamentally is. estar = where it is or what state it is in right now.

Some adjectives change meaning: es aburrido (he is boring) vs está aburrido (he is bored); es listo (clever) vs está listo (ready).

1. Reflexive & 2. Reciprocal

se lava (washes himself) · se abrazan (they hug each other).

3. Impersonal / passive se

"one / people / is done": se habla español (Spanish is spoken) · se venden casas (houses for sale).

4. The no-fault se

Pins an accident on circumstance, not you: se me cayó (it fell, I dropped it) · se me olvidó (I forgot).

5. se = le before lo/la

le lo di is impossible, so le becomes se: se lo di (I gave it to him).

Use the subjunctive (usually after que) when the main clause expresses something not stated as fact. The trigger is WEIRDO:

Also after cuando, hasta que, aunque when the action has not happened yet: cuando llegues, llámame (when you arrive, call me).

The personal "a"

Put a before a specific person used as a direct object. It has no English equivalent.

gustar-type verbs (backwards to English)

The thing is the subject; the person is an indirect object. Literally "X pleases me".

The verb agrees with the thing (gusta / gustan), not the person. Same family: encantar, faltar, importar, doler, parecer, quedar.

Direct object = what/whom the verb acts on (answers "what?"). Indirect object = to/for whom (answers "to whom?"). They use different pronouns in the 3rd person.

DO agrees in gender and number with the noun it replaces: el libro → lo, la carta → la, los zapatos → los, las llaves → las.

Only the 3rd person differs (lo/la/los/las vs le/les). me, te, nos are the same for both.

Pronouns go before a conjugated verb: Lo veo. No la quiero.

With an infinitive or gerund, two positions are both correct, before the whole phrase or attached to the end:

Attaching usually adds a written accent to keep the original stress: come → cómelo, di → dímelo, haciendo → haciéndolo.

When both appear, order is always indirect before direct:

The big rule: le and les become se before lo/la/los/las (you never say le lo):

Because se is ambiguous (him? her? them?), add a él / a ella / a usted / a ellos for clarity: Se lo doy a ella.