How do I use the word "where" as conjunction? Here's a question "This began when I was very young, when I was about 11 years old, I wrote a letter to researcher in the Soviet Union, asking about hypnopaedia, this is sleep learning, you get a tape recorder, you put it beside your bed, and it turns on in the middle of night when you're sleeping, and you are supposed to be learning from this." I don' know why speaker use "where" instead of "which". I think that the meaning of "where" is related to some place or situation and therefore "which" is more appropriate choice than "where". Please let me know why "where" is more natural. Speaking of which, since I started to learn English, I felt baffled when I meet where because I can't understand clearly when to use "where" or " which".