くれる

くれる means "give", but only toward you: someone else gives something to you or to someone on your side – your family, your friends. The giver takes が (or は), the thing given takes を, and the receiver, if you name them, takes に. When the receiver is you, わたくし私に is usually left out.

くれる or あげる

あげる gives away from you: you give, or someone gives to an outsider. くれる gives toward you. Mixing them up is the most common mistake with these verbs.

• × 友達は私に本をあげた → 友達は私に本をくれた
• × 私は友達に本をくれた → 私は友達に本をあげた

てくれる: doing something for you

After a verb in the て-form, くれる says that someone did that for your benefit, and you're grateful for it.

Without くれた, あね姉がしゅくだい宿題をてつだった手伝った only reports what happened. Leaving くれる off a favour done for you can sound ungrateful.

くれる or もらう

もらう tells the same event from the receiver's side: you are the subject, and the giver takes に or から.

Usage notes

These go beyond the plain verb.

くださる

When the giver is above you – a teacher, a customer – くれる becomes the honorific くださる. Its polite form is くださいます, and ください in requests comes from it.

Requests

As a question, くれる? and くれない? ask a favour: てつだって手伝ってくれないきごう？, "could you help me?". That use has its own grammar point.