What it means
どこ means “where” and asks about a place or location. It can ask where a person or thing is, where someone is going, or where an action takes place. It is commonly used with particles such as に, で, へ, and から, depending on the relationship to the place. Both familiar and polite sentences are natural, with the register shown by the surrounding ending.
Usage note
どこに is normally used for a destination or the location of existence, while どこで is normally used for the place where an action occurs. Do not use them interchangeably in standard sentences.
How to use it
図書館はどこですか？
Where is the library?
子どもたちはどこで遊びますか？
Where do the children play?
父はどこに行きますか？
Where is Father going?
図書館はどこだ？
Where is the library?
子どもたちはどこで遊ぶ？
Where do the children play?
父はどこに行く？
Where is Father going?
Example sentences
駅のトイレはどこですか。
Where is the station restroom?
田中さんはどこにいますか。
Where is Mr. Tanaka?
週末はどこへ行きますか。
Where are you going this weekend?
今日はどこで昼ご飯を食べますか。
Where will you eat lunch today?
図書館はどこですか。
Where is the library?
このバスはどこに行きますか。
Where does this bus go?