where

Từ điển American Heritage Dictionary 4th

where (hwâr, wâr)adv.
1. At or in what place:
Where is the telephone?
2. In what situation or position:
Where would we be without your help?
3. From what place or source:
Where did you get this idea?
4. To what place; toward what end:
Where is this argument leading?conj.
1. At what or which place:
She moved to the city, where jobs are available.
2.
a. In a place in which:
He lives where the climate is mild.
b. In any place or situation in which; wherever:
Where there's smoke, there's fire.
3.
a. To a place in which:
We should go where it is quieter.
b. To a place or situation in which:
They will go where they are happy.n.
1. The place or occasion:
We know the when but not the where of it.
2. What place, source, or cause:
Where are you from? [Middle English, from Old English hwǣr. See kʷo- in Indo-European Roots.] 
Usage Note: When where is used to refer to a point of origin, the preposition from is required: Where did she come from? From where I sit, the situation looks bleak. When it is used to refer to a destination, the preposition to is generally superfluous: Where is she going (rather than Where is she going to)? The place where they are going is beautiful. When it is used to refer to the location of a person, event, or structure, the use of at is widely regarded as regional or colloquial: Where is the station (not Where is the station at)? Where he is, he has no access to a good library. See Usage Note at why.