The main rule
y = and, o = or, pero = but, porque = because. Before a word that starts with the sound /i/, y becomes e (padre e hijo); before a word that starts with the sound /o/, o becomes u (siete u ocho). Listen to the sound, not the spelling. Porque (one word) answers; ¿por qué? (two words, accent) asks.
The four connectors
| Connector | Meaning | What it links | Example |
|---|---|---|---|
| y | and | two words, two adjectives, two clauses: it adds | Lucía es alta y simpática. |
| o | or | two options: it offers a choice | ¿Quieres té o café? |
| pero | but | two parts where the second goes against the first | Quiero ir, pero no puedo. |
| porque | because | a result and its reason | No como carne porque soy vegetariano. |
In English, "a" becomes "an" before a vowel sound (a book, an hour), and you decide by how the word sounds, not how it is written. Spanish does the same with y and o, but only for two sounds. The letter h is silent, so hijo starts with /i/ and hielo starts with /je/. English "and" and "or" never change, so the habit has to be built.
y becomes e, o becomes u
| Next word starts with | Change | Example |
|---|---|---|
| the sound /i/ (i-, hi-) | y becomes e | padre e hijo, Pablo e Inés, español e inglés |
| the sound /je/ (hie-) | y stays | agua y hielo |
| any other sound | y stays | Lucía y Marina, pan y leche |
| the sound /o/ (o-, ho-) | o becomes u | siete u ocho, uno u otro, mujer u hombre |
| any other sound | o stays | té o café, hoy o mañana |
The change keeps two identical vowel sounds from running together (y + i, o + o). It applies to numbers written as words too: diez u once, but dos o tres. The names follow the same rule: Javier u Óscar, Pablo e Irene.
Pero and porque
Pero introduces something unexpected after the first part: Tengo hambre, pero no tengo dinero. A comma usually goes before pero. Porque gives the reason and normally has no comma before it: Voy a la farmacia porque estoy enfermo. A correction after a negative (not X but Y) uses a different word, sino, which comes in a later topic.
| Word | Job | Example |
|---|---|---|
| porque | answers: because | A: ¿Por qué no vienes? B: Porque estoy cansado. |
| ¿por qué? | asks: why | ¿Por qué estudias español? |
Examples
- Lucía es alta y simpática. Lucía is tall and nice.
- Tengo un hermano y una hermana. I have a brother and a sister.
- Pablo e Inés son hermanos. Pablo and Inés are brother and sister.
- Estudio español e inglés. I study Spanish and English.
- ¿Quieres té o café? Do you want tea or coffee?
- Son siete u ocho personas. There are seven or eight people.
- Es caro, pero es muy bueno. It is expensive, but it is very good.
- No como carne porque soy vegetariano. I don't eat meat because I am vegetarian.
- A: ¿Por qué no vienes? B: Porque estoy cansado. A: Why aren't you coming? B: Because I am tired.
Say the word out loud
If you are unsure, say the next word and listen to its first sound. If it starts with /i/ or /o/, switch to e or u. If you are unsure between y and pero, ask whether the second part adds something (y) or goes against what you expect (pero).
Common mistakes
padre y hijopadre e hijo hijo starts with the sound /i/, so y becomes e.español y inglésespañol e inglés inglés starts with /i/.siete o ochosiete u ocho ocho starts with the sound /o/, so o becomes u.agua e hieloagua y hielo hielo starts with /je/, not /i/, so y stays.¿Porque no vienes?¿Por qué no vienes? A question needs por qué, two words with an accent.Por qué estoy enfermo.Porque estoy enfermo. An answer is porque, one word, no accent.Quiero ir porque no puedo.Quiero ir, pero no puedo. The second part goes against the first, so it needs pero, not porque.
Frequently asked questions
When do I use e instead of y in Spanish?
Use e before a word that starts with the sound /i/: i- or hi- (padre e hijo, Pablo e Inés). Before hie- the sound is /je/, so you keep y: agua y hielo.
When do I use u instead of o?
Use u before a word that starts with the sound /o/: o- or ho- (siete u ocho, mujer u hombre, uno u otro). Before any other sound, o stays: té o café.
What is the difference between porque and por qué?
Porque (one word, no accent) gives a reason: Porque estoy cansado. ¿Por qué? (two words, accent) asks for it: ¿Por qué no vienes?
Do I put a comma before pero and porque?
Before pero a comma is normal: Es pequeño, pero bonito. Before porque there is usually no comma: No salgo porque estoy cansado.
Is it y or pero when I join two ideas?
Use y to add something (Es pequeño y bonito: both are just facts) and pero when the second part surprises or contradicts the first (Es pequeño, pero muy cómodo). The meaning you want decides.
Does o take an accent between numbers?
No. Today o is written without an accent everywhere, even between figures: 3 o 4. When you write numbers as words, remember the sound rule: siete u ocho, diez u once.