modal particle · sentence-final particle used to express exhortation, urgency, or to soften the tone of a suggestion

大家加把劲哟！

modal particle · interjection expressing slight surprise

哟，外面什么时候下起这么大的雪了？

modal particle · meaningless syllable used as a filler or vocable in song lyrics and folk music

呼儿嗨哟，他是人民的大救星。