代わり

1. Origins, structure, and basic meaning

• Structure: 代わり is read as かわり and means acting in place of someone or using something as a substitute.
• Basic usage: It applies both to doing an action on another person's behalf and to replacing one ingredient with another.

2. Common pitfalls and similar expressions

• In place of a person
  • Nの代わりに, as in 父の代わりに, marks doing something in that person's place. Example: 忙しい父の代わりに私が荷物を受け取った。
• As a substitute item
  • Nの代わりとして presents something as a material or means used instead of the preceding item. Example: 牛乳の代わりとして豆乳を使った。