EmberJS app and Broccoli

I have an Ember app (which is actually an addon/engine). My question is very basic (regarding the usage of Broccoli)

Now it is said that Broccoli is the default build tool for Ember-CLI

But I do not find Brocfile.js anywhere within my project.

Just wanted to understand how is Broccoli really used within an Ember project. Also in what practical scenarios do we have to change/define any configurations related to that