In the continuation of a series on building a real-time RFID application with Tessel and PubNub, this entry explores how to act on RFID events by setting up Tessel to read RFID cards, publishing unique identifiers (UIDs) to a channel, and modifying code to display and authorize these UIDs. It provides detailed instructions on interpreting Tessel RFID events, matching them against a list of valid RFIDs, and modifying existing HTML and AngularJS code to reflect UID detections. The guide explains how to set up the Tessel device, adjust the project code to replace 'uuid' with 'uid', and visually indicate authorization status by modifying the HTML to represent whether a device is authorized, using green and red colors. It also suggests further customization by incorporating additional data such as owner information.