-요

• 예 (-ye, dialectal), 여 (-yeo, spelling pronunciation of modern Seoul, used for "cutesy" effect)

First widely attested in late eighteenth- and nineteenth-century novels intended for popular consumption. Stems from a contraction of 이오 (-i-o, “it is that...”), from 이 (-i-, “to be”, copula) + 오 (-o, declarative verbal suffix of the semi-formal speech level).[1][2] The suffix 오 (-o) itself goes back to Middle Korean -ᅀᆞᇦ〯- (-zǒW-, object honorific verbal suffix), though the exact derivation is unclear, and ultimately to Old Korean 白 (*SOLP-, “to inform a superior”).[3]

• (SK Standard/Seoul) IPA^(key): [jo] ~ [jʌ̹]
• Phonetic hangul: [요/여]

요 • (-yo)

1. A particle attached to intimate-style verbs and adjectives to form the polite style, the usual speech level for polite but not extremely formal conversation, e.g. by a student to a teacher, a child to a parent, or between colleagues.

   해요. ― Hae-yo. ― Let's do it.

   안녕하세요. ― Annyeonghase-yo. ― Hello.

   제가 도와드리지요. ― Je-ga dowa-deuriji-yo. ― I can give you a hand.

• 요 (-yo) is the traditional, prescriptive pronunciation; 여 (-yeo) is a common alternative pronunciation by young South Koreans.
• For the copula 이다 (-ida, “to be”) and 아니다 (anida, “to not be”), the form is irregularly 이에요 (-i-eyo).
• For the honorific 으시 (-eusi-), the form is irregularly 으세요 (-euseyo).
• In the polite style, there is no explicit marker to distinguish between indicative, interrogative, imperative, and hortative moods. The distinction is made only by pitch in speech (e.g. rising pitch for questions), and by punctuation in writing.