used in questions
You use where to ask questions about place or position.
Where does she live?
You also use where to ask about the place that someone or something is coming from or going to.
Where are you going?
Where does all this anger come from?
used in place clauses
You use where in place clauses when you are talking about the place or position in which someone or something is.
He said he was happy where he was.
He dropped the ball and left it where it lay.
A place clause usually goes after the main clause. However, in stories, the place clause can be put first.
Where the house had once stood, there was an empty space.
Where the sun touched the water it shone like gold.
used in reported clauses
Where is often used in reported clauses.
I think I know where we are.
I asked someone where the nearest hotel was.
used in relative clauses
Where is often used in non-defining relative clauses.
He comes from Canterbury, where the famous cathedral is.
She went into the art room, where the brushes and paint had been set out.
Where can also be used in defining relative clauses after place or after a word such as room or street.
Will you show me the place where you work?
The room where I did my homework was too noisy.
Where can also be used in defining clauses after words such as situation and stage.
We have a situation where people feel afraid of going out.
I've reached the point where I'm ready to retire.
used with ‘possible’ and ‘necessary’
Where is sometimes used in front of adjectives such as possible and necessary. When it is used like this, it has a similar meaning to ‘when’ or ‘whenever’.
Where possible, friends will be put in the same class.
Help must be given where necessary.