This document presents a comparison of popular digital assistants: Siri, Cortana, Alexa, and Google Now. It discusses each assistant's functionality, with Siri focusing on questions and answers through optimized search, Cortana providing a virtual interface for Windows devices, Alexa as a voice assistant through Amazon's Echo, and Google Now delivering personalized information and recommendations based on user preferences and search history. The document concludes that voice interfaces will continue becoming more integral in daily life for tasks like home device control and in-car information and entertainment systems, improving safety and convenience through hands-free interaction.