"피곤해요"

Translation: I am tired

[Serieve]

So this 요 is slightly less formal than 니다 endings, right? My impression is 요 is more common but still polite, while 니다 is particularly polite. Is that correct?

[wintertriangles]

Yep. 요 is how you'd speak with strangers. ㅂ니다 is how you'd speak to someone "important." Sometimes people just use "요" with grandparents depending on the grandparents. The news and radio will use ㅂ니다 though.