What does the e-tron button do in an Audi?

I'm confused about the e-tron button found on the dashboard of an Audi. Can someone explain its purpose and how it works?

The e-tron button is part of the Audi electric powertrain system. It allows you to switch between all-electric mode, hybrid mode, and charging mode depending on your driving needs. Simply press it to change modes.

The e-tron button is a convenient way to access all the e-tron features in one place. It also includes efficiency functions such as recuperation and coasting, allowing for a more efficient drive.