We use 'where' to ask questions about a place. It helps us find out the location of a thing or person. It is very common in daily speech.
Where is my book?
Where do you live?
'Where' can connect two parts of a sentence to show the place of something. It tells us the place where an action happens.
This is the house where I was born.
I know a place where you can rest.
'Where' can link two ideas and show difference or contrast. It means 'but' or 'although' in formal writing.
He likes coffee, where I prefer tea.
She works at night, where I sleep.
'Where' can talk about a situation or condition, not just a physical place. It is used in general or abstract ideas.
Where there is smoke, there is fire.
I do not know where this will end.
In formal or literary use, 'where' can show cause or reason. It means 'because' or 'since' in these sentences.
Where anger rules, peace fades.
Where one door closes, another opens.