A barrel is a way to rollup exports from several modules into a single convenient module. The barrel itself is a module file that re-exports selected exports of other modules.
It's easier to import from a module in one statement, rather than three separate import statements.
import { FooComponent, BarComponent, FooBarComponent } from 'your-module';`
Barrel files are named index by convention.
A nice side-effect is that it avoids duplicate names of the folder and the component, e.g. import { Component } from '../Component/Component'
Note that you can't use the barrel export inside your module, as it will lead to circular dependencies. Similarly, importing from a barrel file can lead to adding unnecessary code to your bundle. As far as I understand, one import leads to effectively importing everything within the barrel file. [[20220912113840-tree-shaking]] is a often used as a solution to this problem.
https://github.com/basarat/typescript-book/blob/master/docs/tips/barrel.md