This document discusses Professional Learning Networks (PLNs) and how Twitter can be used to build a PLN. It provides definitions of a PLN as a deliberately formed network of people and resources to support independent learning and professional development. The document then discusses how the author built her PLN on Twitter over the course of a semester by following relevant accounts, and provides screenshots tracking the growth of her network and followers. She explains how PLNs allow teachers to connect, collaborate and contribute through sharing ideas and perspectives on education topics on Twitter.