どこ

1. Origins, structure, and basic meaning

• Structure: どこ stands for a place in a question and takes a particle suited to that place's role.
• Basic usage: It asks where something is or where an action will take place.
  • 駅はどこにありますか。 asks for the station's location.

2. Common pitfalls and similar expressions

• Role of the location being asked about
  • どこで食べますか asks where someone will eat, どこへ行きますか where they are heading, and どこから来ましたか where they came from. The general meaning of 'where' does not remove the need for the appropriate particle.
• Somewhere and nowhere
  • どこかにあります states that something is somewhere, while どこにもありません states that it is nowhere. The latter combines にも with a negative predicate.
• Embedded questions
  • 駅がどこにあるか知っていますか asks whether someone knows the station's location. A location question can be embedded using a unit such as どこにあるか.