Design Twitter.

Focus on the core functionalities that make Twitter unique, such as real-time tweet posting, retweeting, and following mechanisms. Consider the user experience for both mobile and web interfaces, emphasizing simplicity and speed. Discuss how you would handle scalability to accommodate millions of users and tweets, including data storage and retrieval. Address the challenges of content moderation and user safety, outlining potential solutions. Finally, think about how to incorporate features that enhance user engagement, such as trends, hashtags, and notifications.