"Before" means "prior to a point in time"; "ago" measures time back from the present moment.
Earlier than a point in time or event. Can precede nouns, clauses, or stand alone.
I had never seen snow before I moved to Canada.
Nunca habia visto nieve antes de mudarme a Canada.
Please read the instructions before you start.
Por favor lee las instrucciones antes de empezar.
Have you been to Paris before?
¿Has estado en Paris antes?
X time in the past from now — always measured from the present, always with simple past.
I moved to Canada three years ago.
Me mude a Canada hace tres anos.
She called me a few minutes ago.
Ella me llamo hace unos minutos.
We met a long time ago, but I still remember.
Nos conocimos hace mucho tiempo, pero aun lo recuerdo.
Common mistake
Classic error: "I saw that movie three years before." Wrong — "before" needs a reference point ("before dinner") or a perfect tense context. To measure time back from now, use "ago": "I saw that movie three years ago."
Trick to remember it
Trick: "ago" always comes AFTER the time period and always pairs with simple past. "Three years ago / five minutes ago / a long time ago." The formula is: [time period] + ago.
Quick rule
X time ago = X time in the past from now (simple past). Before = prior to a reference point.
Did you know?
"Ago" comes from Old English "agan" meaning "to pass" or "to go by". In formal or literary English you still find "long ago" and "ages ago". The phrase "once upon a time" is the narrative version of "a long time ago" — both signal a distant past without a specific date.
Exercise 1 · Pick the right one
We moved to this city exactly five years _____.
Exercise 2 · Pick the right one
She had never tried sushi _____ she visited Japan.
Exercise 3 · Form the word
X time ago = X time in the past from now (simple past). Before = prior to a reference point.
Classic error: "I saw that movie three years before." Wrong — "before" needs a reference point ("before dinner") or a perfect tense context. To measure time back from now, use "ago": "I saw that movie three years ago."
Trick: "ago" always comes AFTER the time period and always pairs with simple past. "Three years ago / five minutes ago / a long time ago." The formula is: [time period] + ago.
Bryan López
Founder of SpeakUP Academy