Several parts combine into one character.

情 is a phonetic-semantic compound: 忄 (the heart radical, an upright stylized form of 心) plus 青 (qīng, "clear blue-green"). The composite captures something subtle — the heart in its clear, transparent state, untainted by deception. 情 is part of the famous 青-family of phonetic-semantic compounds (青 + 氵 = 清 clear water; 青 + 心 = 情 clear heart; 青 + 立 = 静 quiet) that all share the sound qīng/jeong/sei and the meaning of clarity.

Korean reading "jeong." This single character generates one of the most culturally loaded words in Korean: (jeong) — an affectionate, slow-grown attachment that is considered uniquely Korean and notoriously difficult to translate. Even though the character is shared, the depth of 정 as a Korean cultural concept is distinctive. 感情 (gamjeong, emotion), 愛情 (aejeong, affection), 情報 (jeongbo, information — note the surprising semantic leap from "feeling" to "information"), 事情 (sajeong, circumstances), 熱情 (yeoljeong, passion), 人情 (injeong, "human feeling" / kindness).

Mandarin qíng, 2nd tone. 感情 (gǎnqíng, emotion), 爱情 (àiqíng, romantic love), 事情 (shìqing, matter / affair — high-frequency), 情况 (qíngkuàng, situation), 心情 (xīnqíng, mood). Chinese semantic split: 感情 = deep emotion; 心情 = passing mood. The two are not interchangeable, and learners commonly confuse them.

Japanese on-reading ジョウ (jō) — 感情 (kanjō, emotion), 情報 (jōhō, information), 愛情 (aijō, affection), 友情 (yūjō, friendship), 事情 (jijō, circumstances). Note the same "feeling → information" semantic leap occurs in 情報 — possibly from the Meiji-era coinage of new concepts using classical Chinese morphology. The kun-reading なさけ (nasake, "compassion / mercy") survives in literary phrases: 情けは人のためならず ("kindness is not just for the other person's sake") — a famous Japanese proverb.

Memory aid: a heart (忄) clear like blue water (青) — the genuine, unclouded feeling.