hanamaru
Distance is measured from the speaker
こ is near me, そ is near you, あ is far from us both. The same three sounds run this/that, this book, here/there.
こ・そ・あ・ど
near me
near you
Japanese picks the word by where the thing is in relation to the speaker. こ-words are for what is near me: これ, this one. そ-words for what is near the person I am talking to: それ, that one. あ-words for what is far from us both: あれ, that one over there. The picture above shows the zones.
Distance is always measured from whoever is speaking, so the same thing changes its name when the turn passes. A book on the table in front of you is これ when you talk about it and それ when the other person answers. On the shelf by the far wall it is あれ for both of you. The book does not move — the voice does.
The same three sounds start more words. Before a noun they become この, その, あの: この ほん, this book. For places ここ, そこ, あそこ: here, there, over there. And the question starts with ど: どれ, which one; どの, which + thing; どこ, where. Learn the sound and you have the whole row.