ていく【～ていく】

ていく joins the て-form of a verb to いく, "go". Its most literal use is doing something and then going, or taking something with you as you go.

もっていく持っていく is "take" a thing and つれていく連れていく is "take" a person or an animal. いく is usually written in kana here, and in casual speech ていく shortens to てく: 持ってく.

ていく or てくる

てくる moves towards where you are now, ていく away from it. Going to the listener's place counts as going, so Japanese uses ていく where English says "bring".

• × (on the phone to the host) 明日ケーキを持ってきます → 明日ケーキを持っていきます

Change from now on

With a verb of change, ていく says it will carry on from now into the future. てきた looks back at a change that has led up to now.

Keep on doing

With an ordinary action, ていく says you will keep at it from here on, often as a resolution.

Moving away

With a verb of motion, ていく shows the movement heading off from the speaker.