Intro and Set in motion

Intro noun - A short section (as of a book) that leads to or explains the main part.

Set in motion and intro are semantically related in start topic. In some cases you can use "Set in motion" instead a verb "Intro", when it comes to topics like initiate.

Set in motion verb - Get going; give impetus to.

Intro and set in motion are semantically related in start topic. Sometimes you can use "Intro" instead a verb phrase "Set in motion", if it concerns topics such as initiate.