Several parts combine into one character.

Compound ideograph: 門 (gate / double doors) with 开 inside (two hands lifting a crossbar). The encoded scene is direct: hands lifting the wooden bar that locks a gate, opening it. The character itself shows the action. Three forms with significant divergence: 繁體 開 / 新字体 開 / 简体 开 (the gate frame disappears entirely, leaving only the crossbar-lifting hands).

开 / 開 anchors a huge family of "opening / starting" verbs: 開始 / 开始 (start), 開発 / 开发 (develop), 公開 / 公开 (make public), 開放 (open / liberalize), 開幕 / 开幕 (open the curtain — beginning of a performance).

Mandarin: kāi, level 1st tone (simplified 开). One of the most heavily used verbs in Mandarin: 开 (kāi, to open), 开始 (kāishǐ, to begin), 开门 (kāimén, open the door), 打开 (dǎkāi, open / unfold), 开车 (kāichē, drive a car — "open the vehicle"), 开会 (kāihuì, hold a meeting), 离开 (líkāi, to leave), 开心 (kāixīn, happy — "open heart"), 开玩笑 (kāi wánxiào, to joke). The verb 开 attaches to many objects to mean "operate / activate them" — 开车 (drive), 开灯 (turn on lights), 开火 (open fire).

Japanese: on-reading カイ (kai) for compound nouns — 開発 (kaihatsu, development), 開始 (kaishi, start), 公開 (kōkai, public release), 開幕 (kaimaku, opening / curtain rise — used for sports seasons and theatrical events). Kun-readings split between intransitive and transitive: ひら.く (hira.ku, to open / bloom — flowers, books), あ.く (a.ku, to open intransitively — door opens by itself), あ.ける (a.keru, to open transitively — I open the door). Three different verbs from one character — Japanese learners must memorize each.

Memory aid: a gate with two hands lifting the crossbar — opening encoded as a literal scene.