What's the difference between ending an answer with だ vs だよ・です?


I was talking to someone and they asked me:

> 出身はどこなの？

to which I responded saying:

> イギリス出身だ

My friend then told me that that sounded a bit strange, and it would have
sounded more natural if I had responded with either one of these instead:

> イギリス出身だよ
>
> イギリス出身です

I don't quite get the difference in nuances between all of these, and I was
hoping someone could help explain why the だ ending sounds weird, whereas the
other two sound fine? Also, why is it that です without a よ after it is
acceptable, whereas だ _must_ be followed by a よ?




Sentence endings are important but not simple. You'll need to learn by
examples. Here's the summary:

  * **イギリス出身です** : Polite form. Safe in business settings or when talking with a stranger.
  * **イギリス出身ですよ** : Polite form followed by よ. よ is not necessary, but it indicates you are trying to explain something meaningful, like "you know" in English.
  * **イギリス出身だ** : Plain form. Used in essays or news articles, but sounds fairly blunt in speech. A difficult boss or a dignified knight may speak like this in fiction.
  * **イギリス出身だよ** : Plain form followed by よ. Safe when talking with your friends or classmates, but overly friendly in business settings.

If you already know polite form and are trying to speak casually, probably the
safest option in real-life conversations is "イギリス出身。" followed by nothing.

