Several parts combine into one character.

The traditional 禮 is a compound ideograph: 示 (the "altar" radical, depicting an ancestral altar with offerings) + 豊 (fēng, "abundance" — itself a pictograph of a ritual vessel piled high with food offerings). The composite scene is unmistakably ritual: presenting bountiful offerings before an altar to honor spirits and ancestors = ceremonial conduct, propriety, etiquette. From this sacred ceremonial origin grew the entire vocabulary of social courtesy: ritual → propriety → etiquette → polite behavior → return courtesy. Japan and Mainland China both simplified to 礼, keeping only the altar radical with a small mark. Korea retains the elaborate 禮.

禮 is one of the four cardinal Confucian virtues alongside 仁 (benevolence), 義 (righteousness), and 智 (wisdom). It anchors the entire framework of East Asian social conduct.

Korean reading "rye" (or "ye" word-initially per phonotactic rules). 禮儀 (yeui, manners / etiquette — what every Korean child is told to learn), 禮節 (yejeol, propriety), 儀禮 (uirye, ritual / ceremony), 答禮 (damnye, return courtesy / reciprocal politeness), 禮拜 (yebae, worship — used in Christian church contexts: 예배당 yebaedang = chapel), 婚禮 (hollye, wedding ceremony). 예의 saturates Korean vocabulary about respect.

Mandarin lǐ, 3rd tone. 礼 (lǐ), 礼貌 (lǐmào, "ritual-appearance" = manners / politeness — 有礼貌 = polite, 没礼貌 = rude), 礼物 (lǐwù, "ritual-thing" = gift — beautiful Chinese coinage: a gift is a tangible ritual offering), 婚礼 (hūnlǐ, wedding), 敬礼 (jìnglǐ, salute), 礼品 (lǐpǐn, present). 礼物 is the standard Mandarin word for "gift" and reveals the conceptual link: every gift carries ritual significance.

Japanese on-reading レイ (rei) — 礼儀 (reigi, etiquette), 礼拝 (reihai, religious worship), 敬礼 (keirei, salute — used for military and ceremonial bow), and most importantly 失礼 (shitsurei, "losing politeness" = "excuse me / pardon me / I beg your leave"). 失礼します (shitsurei shimasu, "I will commit a discourtesy") is one of the most common phrases in everyday Japanese — used when entering or leaving a room, when interrupting, when asking a question, when ending a phone call. The phrase humbly acknowledges that one's presence may inconvenience others. Alternative on-reading ライ (rai) — 礼讃 (raisan, praise / glorification — Buddhist context).

Memory aid: an altar (示) with abundant offerings (豊) — ritual ceremony became the foundation of all etiquette.