Incorporating a "who's online" feature in applications can significantly enhance user engagement, particularly in environments such as chat rooms, collaborative platforms, or online gaming. This guide details the integration of Pusher Presence channels with User Authentication to create this feature, offering real-time notifications about users entering or leaving a channel. Presence channels notify subscribed users about these changes, while User Authentication simplifies user identification and connection processes. The example provided focuses on a chat application where users can see others' icons, names, and roles, with different chat rooms offering varying levels of user information. The implementation steps include initializing Pusher on client devices, setting up user authentication to identify logged-in users, and using Presence channels to manage user interactions. Additionally, channel-specific user information can be provided to tailor the experience based on the type of chat room, such as indicating admin roles in business-related discussions. This setup enables real-time updates and personalized user engagement across various applications.