Several parts combine into one character.

The traditional 筆 is a beautifully self-explanatory compound ideograph: ⺮ (bamboo) sitting atop 聿 (a hand gripping a writing brush — the original pictograph of the brush itself). The composite picture is exactly an East Asian writing brush: a tuft of animal hair set into a bamboo handle, held in the hand. This is the original technology of CJK literacy — every classical text was written with this implement, and the character documents the tool that made the entire civilization possible. Mainland China simplified to 笔, an even more transparent ideograph: 竹 (bamboo) over 毛 (hair / fur). One character became more pictographic in its simplified form than its complex original.

Korean reading "pil." 筆記 (pilgi, written notes / written exam — central to Korean educational vocabulary; the contrasting term is 실기 sil-gi for practical/skill examination), 鉛筆 (yeonpil, pencil), 萬年筆 (mannyeonpil, "ten-thousand-year pen" = fountain pen — a beautiful CJK coinage referencing durability), 毛筆 (mopil, calligraphy brush), 絶筆 (jeolpil, "final brushwork" = an artist's last work before death), 筆順 (pilsun, stroke order — essential to learning kanji properly).

Mandarin bǐ, 3rd tone (simplified 笔). 铅笔 (qiānbǐ, pencil), 钢笔 (gāngbǐ, "steel pen" = fountain pen), 毛笔 (máobǐ, brush), 圆珠笔 (yuánzhūbǐ, "round-bead pen" = ballpoint pen), 笔记本 (bǐjìběn, notebook). The compound 笔记本电脑 (bǐjìběn diànnǎo, "notebook electric brain") is the standard Mandarin word for laptop computer — illustrating how the ancient brush character continues to anchor modern technology vocabulary.

Japanese on-reading ヒツ (hitsu) — 筆記 (hikki, note-taking), 万年筆 (mannenhitsu, fountain pen), 絶筆 (zeppitsu, final work). Kun-reading ふで (fude) — 筆 (fude, brush), 筆箱 (fudebako, pencil case — even now that fude has been displaced by pencils, the compound preserves the ancient term). The classical phrase 一筆書く (ippitsu kaku, "to write a single brushstroke") is an elegant way to mean "to dash off a brief note or letter" — preserving the dignity of brush-and-ink correspondence even in the email age.

Memory aid: bamboo (⺮) over a hand-gripped brush (聿) — the literal picture of an East Asian writing implement.