We use 'upon' to say that one thing is directly on another thing. It means the same as 'on' and shows touching or resting.
The book is upon the table.
He put the hat upon his head.
'Upon' means something happens just after another event. It shows time, like 'right after' or 'when'.
Upon arrival, call me at once.
She smiled upon hearing good news.
'Upon' is used to say something depends on or comes from information, ideas, or facts. It means 'based on'.
Decisions were made upon new evidence.
The story is based upon real events.
'Upon' is used in formal writing or law. It means 'in case of' or 'about' someone or something.
Upon default, penalties will apply.
Guidelines upon students' conduct are strict.
'Upon' can show that an action happens right after another. It is common in phrases meaning 'as soon as'.
They acted upon hearing the alarm.
Upon entering, please sign in.
In poetry or old English, 'upon' means on a surface or higher place. It shows something resting or located above.
The knight stood upon the hill.
Clouds floated upon the mountains.
'Upon' can show that something has an effect or influence on a person, group, or thing.
The new law had an effect upon farmers.
Stress has a strong impact upon health.
