Several parts combine into one character.

In oracle bone script, 買 shows 网 (a net) on top of 貝 (a cowrie shell — ancient Chinese currency). The mental image is vivid: someone gathers coins in a net to scoop them up and exchange them for goods. "To buy" was depicted as the act of pooling money. The character is nearly identical across CJK — Japan and Korea use 買, while Mainland simplified it to 买 (replacing the 网 net with a simpler shape).

Korean reading "mae" — same sound as 賣 (sell), the two pair like inseparable twins. 購買 (gumae, purchase), 賣買 (maemae, transaction), 買收 (maesu, buyout / corruption / bribery), 買入 (maeip, purchase). The Korean compound 買收 carries an extra dark sense of "buying influence" — bribery — alongside the literal "buy out."

Mandarin mǎi, 3rd tone (simplified 买). One of the very first verbs any Chinese learner meets: 买东西 (mǎi dōngxi, to buy things — literally "buy east-west"), 购买 (gòumǎi, to purchase), 买单 (mǎidān, to pay the bill). Critical pronunciation note: 买 (mǎi, buy, 3rd tone) and 卖 (mài, sell, 4th tone) differ only by tone — beginners constantly say "I want to sell apples" when they mean "buy apples." The 3rd tone dips down (the buyer "lowers" his money); the 4th tone falls sharply (the seller "delivers" the goods).

Japanese on-reading バイ — 売買 (baibai, transaction), 購買 (kōbai, purchasing). Kun-reading かう (kau, to buy) — 買う is among the highest-frequency verbs in spoken Japanese, and 買い物 (kaimono, shopping) is a daily-life staple word.

Memory aid: 网 (net) gathering 貝 (coins) — pulling money together to buy.