Do or Ydw?

I know there are many ways to say yes and no in Welsh, and I’ll probably learn them as the challenges progress. However up to the end of level 1 I have been hearing Do and Ydw and I’m a bit confused as to when to use each one. I thought that Do was always used to answer a question but that doesn’t seem to be the case, or have I missed something here?

Do and naddo are a pretty much catch all answer to past tense questions (there are others but don’t worry … yet). “Est ti i’r dafarn ddoe?” … “Do.” (Did you go to the pub yesterday? Yes.)

Ydw and nac ydw are yes and no when asked about yourself like “wyt ti’n siarad Cymraeg?” … “Ydw.”


Thanks Gruntius, that’s helpful.