We use 'per' to say how much or how many there are of something for each unit or person. It shows a rate or amount for every one item or person.
The cost is five dollars per book.
She runs three miles per day.
'Per' is used to say where information or instructions come from. It means 'according to' something like rules, laws, or reports.
Per the rules, you must stop here.
Per the weather report, it will rain.
In formal use, 'per' can mean 'by' or 'through' a person or method. It shows how something is done or who does it.
Send the letter per courier service.
The message was sent per email.
'Per' is sometimes used as a short way of saying 'percent' in formal or old texts. It shows a part of one hundred.
Ten per of the people agreed.
This is five per more than before.
In music, especially in scores, 'per' is used as short for 'percussion', the family of instruments like drums and cymbals.
The per part starts at measure ten.
The band needs a per player.
Rarely, 'per' can be a verb meaning to pass through or across something. This is an old or dialect form and is not common today.
He will per the gate to enter.
They per the forest quietly.
