Yesterday
Use this to mean 'last night'. It's more specific than 'ayer'.
Use this to mean 'the day before yesterday'. It's also sometimes written as 'anteayer'.
A slightly more formal way to say 'the day before', often used when telling a story.
Yesterday I spoke with my sister.
What did you eat last night at the restaurant?
My flight arrived the day before yesterday in the morning.
The party was on Monday. The day before, we prepared everything.
The word 'ayer' is standard and understood everywhere in the Spanish-speaking world, from Mexico to Spain to Argentina. There are no significant regional differences for this specific word.
The pronunciation of the 'y' in 'ayer' sounds more like 'sh' (ah-SHER). This is a characteristic of the 'Rioplatense' accent but the word itself remains the same.
Using the present tense with 'ayer'. For example: *'Ayer voy al mercado.'* — The word 'ayer' signals that an action happened in the past, so you must use a past tense verb. The correct sentence is 'Ayer fui al mercado' (Yesterday I went to the market).
Confusing 'ayer' (yesterday) with 'mañana' (tomorrow). — These are opposites and a common point of confusion for beginners. Practice them together: 'Hoy' (today), 'ayer' (yesterday), 'mañana' (tomorrow).
Mispronouncing the 'y' sound. English speakers often say 'ah-jer' like the 'j' in 'jet'. — In most of Latin America, the 'y' sounds like the 'y' in 'yes'. Focus on making that sound: ah-YEHR.