How does Google Docs work?

Focus on the architecture and key technologies that enable Google Docs to function in real-time. Discuss the collaborative features, such as how multiple users can edit simultaneously and how changes are synced across devices. Highlight the backend infrastructure, including the use of cloud storage and databases, as well as any relevant protocols like WebSockets for real-time communication. Consider mentioning how Google ensures data security and version control, as these are critical for user trust and functionality.