Some embodiments include a messaging system capable of expression-based communication and/or expression-based actions. The messaging system can run on a computing device. For example, the messaging system monitors a camera feed from a camera of the computing device to detect a biometric signature when a messaging interface of the messaging application is actively being used. The messaging system can match the detected biometric signature against a known profile utilizing a facial recognition process to authenticate an operating user to use the messaging application. The messaging system can determine a human expression based on the detected biometric signature utilizing an expression recognition process to associate a contextual tag with an activity on the messaging interface. The messaging system can then communicate with a message server system to associate the contextual tag with content presented to the operating user or a conversation participated by the operating user via the messaging application.