What asks for a definition, a general explanation or the name of something when it has not been identified before. It appears in questions like ¿Qué es eso? or ¿Qué significa esta palabra? It also works when you want to know what happens: What’s going on?

Which is used to select or choose among options, or to ask for a concrete answer within a known group. That’s why it sounds natural in questions like ¿Which do you prefer? or ¿Which is your phone number? When the question does not seek a definition but rather a choice, which fits best. In many contexts, Pronombres Interrogativos and Adjetivos Interrogativos show the same contrast between asking for general information and asking for a precise selection.

Basic difference between what and which

Idea
Use qué to ask for a definition or a general explanation.
Use cuál to choose among options or ask for a concrete answer.

Who asks about a person. It is used to ask for someone’s identity: ¿Quién llamó? or ¿Quién es esa mujer? When the answer includes several people, quiénes is used: ¿Quiénes vienen a cenar?

With a preposition, the form keeps the tilde: ¿Con quién hablas?, ¿De quién es este libro?, ¿Para quién compraste eso? In more formal questions, the preposition usually comes before, and the interrogative comes after. That pattern also appears in Pronombres Interrogativos, where the same form can work alone or accompanied by a preposition.

Questions about people and plural

Idea
Use who to ask about a single person.
Use who to ask about several people.
Use of whom when the question has of in front.

Where asks about a place or location: ¿Dónde vives?, ¿Dónde está el banco? The answer usually names a site or position.

To where asks about destination or direction. It is used when there is real movement or a sense of motion: ¿Adónde vas?, ¿Adónde llevan las cajas? If the question points to the place someone or something is heading, to where is the appropriate form. This contrast relates to Adverbios de Lugar, because both talk about spaces, but to where adds goal or destination.

Place and destination in questions

Usage	Explanation
Static place	Use where when you ask about a place where someone or something is or happens.
Destination or direction	Use where to when you ask about the destination of movement or of a trip.

In the everyday speech of many countries, dónde also appears where more careful usage prefers adónde. You often hear ¿Dónde vas? to ask about destination, even though the question expresses movement.

In formal registers, in edited texts, and in situations where precision is sought, it is advisable to maintain the difference: dónde for place and adónde for destination. The distinction remains useful when the direction of movement matters, especially together with movement verbs like ir, venir, llevar or mandar.

adóndedóndedónde

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En contextos cuidadosos se reserva para el destino y ayuda a marcar mejor el movimientoEn el habla cotidiana puede aparecer para destino incluso cuando en un registro más cuidado se esperaría adóndeEn el habla cotidiana se usa mucho para lugar y también para destino aunque la diferencia formal siga existiendo

Everyday use of dónde and adónde

Region	Variant	Definition	Example
Spain	dónde	In everyday speech it is used a lot for place and also for destination although the formal difference still exists.	¿Dónde vas con ese paraguas dentro de casa¿Where are you going with that umbrella inside the house
Mexico	dónde	In everyday speech can appear for destination even when a more careful register would expect adónde.	¿Dónde te fuiste tan temprano a comprar tacos¿Where did you go so early to buy tacos
Argentina	adónde	In careful contexts it is reserved for the destination and helps to mark movement better.	¿Adónde corriste con tanta prisa después del mate¿Where to did you hurry after the mate

Scramble

When asks for a temporal reference. It is used to ask about a moment, a date, a time or a stage: ¿Cuándo llegas?, ¿Cuándo empieza la clase?, ¿Cuándo fue la reunión?

It can refer to an exact instant or to a broader period, depending on the expected answer. It also appears in questions about habits or plans: ¿Cuándo suelen abrir? and ¿Cuándo piensas viajar? If the information sought is in time, when fits directly.

Questions about time

Usage	Explanation
Exact moment	Use when to ask for the moment at which something occurs.
Date or deadline	Use when to ask for a date or a time limit.
Temporal situation	Use when also to ask for a time period or time circumstance.

How asks about mode, manner, state or way of doing something: ¿Cómo cocinas este arroz?, ¿Cómo estás?, ¿Cómo funciona? It does not seek a place or a time, but the way in which something occurs or is carried out.

It often appears with action verbs, but also with state verbs. That is why it can ask for a description of the situation: ¿Cómo está tu madre? or an explanation of the procedure: ¿Cómo se abre esta puerta? In Adverbios de Modo you see the same idea in statements like habla bien or trabaja despacio, where the manner of acting is described.

Questions about manner and state

Usage	Explanation
Manner of doing something	Use how to ask about the manner in which an action is performed.
State or condition	Use how to ask about the state of a person or thing.
Form or appearance	Use how to ask about the form or appearance of something.

How much, how many, how many, and how many ask about quantity. They agree with the noun they accompany: ¿Cuánto tiempo falta?, ¿Cuánta agua quieres?, ¿Cuántos libros compraste?, ¿Cuántas personas vinieron?

The form changes in gender and number like an interrogative adjective. If the noun is masculine singular, it’s cuánto; if feminine singular, cuánta; in plural, cuántos and cuántas. They can also appear without a noun when the quantity is understood from context: ¿Cuántos hay? In Adjetivos Interrogativos this agreement is shown in more detail, because the word directly accompanies the noun.

Quantity and interrogative agreement

Idea
Use how much with masculine singular nouns.
Use how much with feminine singular nouns.
Use how many with masculine plural nouns.
Use how many with feminine plural nouns.

Why asks about cause or motive: ¿Por qué llegaste tarde?, ¿Por qué estudias español? The answer usually introduces the reason with porque, ya que or debido a que.

The interrogatives also carry an accent in indirect questions, even if the question mark does not appear: No sé por qué llegó tarde, Quiero saber quién llamó, Explícame dónde vive. In those sentences, the word retains its interrogative or exclamatory value inside a larger clause. That difference is key to distinguishing por qué from the causal conjunction porque.

Reason and accent in indirect questions

Idea
Use why to ask for cause or motive.
Use qué with an accent when it appears in an indirect question.
Use cuál with an accent when it appears in an indirect question.