This article explains how to enable double-sided printing on a Mac when using an application or browsing the web. Instructions apply to Macs running macOS Catalina through OS X Lion.
Printing on the front and back of pages is easy on a Mac, especially when using an app like Microsoft Word (or another Microsoft Office app).
For example, here's what to do if you've typed a Word document on your Mac and want to print it double-sided:
Connect your Mac to a printer that can print on both sides of the paper (duplex).