为【wèi / wéi】

为 has two readings. Read wèi, it means "for": whom an action benefits, or what it is done for. Read wéi, it means "as", "into" or "to be", in formal writing, usually straight after another verb.

为someone

为 + person goes before the verb, never after it as English "for" does. It is more formal than 给: 给 hands something over, while 为 says on whose behalf or to whose benefit.

• × 他准备了晚饭为大家 → 他为大家准备了晚饭

为…而…: for a cause

With 而 before the verb, 为 names the cause or the reason: 为 + noun + 而 + verb. The pattern is written and a little solemn.

为了 is the everyday "in order to" and has its own entry.

为into, to be

After verbs such as 成, 作, 选, 改, 分, 称 and 翻译, 为 means "as" or "into": 成为 "become", 改为 "change to", 分为 "divide into". In a notice, 为 on its own is a written 是.

以…为… and the passive 为…所 also use 为wéi, and have their own entries.