X started as Twitter in 2006. Elon Musk bought it in 2022 for $44 billion and renamed it a year later. Ownership has shifted twice since: first to xAI (Musk's AI company) in March 2025, then to SpaceX in February 2026. The core product is short-form posting, trending topics, direct messaging, and Grok, an AI chatbot baked into the platform.

Your posts train Grok by default. X processes roughly 500 million posts per day and feeds them into its AI models. No opt-in required. A 2024 study found 73% of users had no idea this was happening. To stop it, you have to dig into your privacy settings and toggle the option off yourself. Even after that, X still reserves the right to use your posts internally.

Security has been a recurring problem. In January 2025, a 400GB dataset with records linked to 2.8 billion accounts appeared online. The leak is believed to involve a company insider during mass layoffs. A separate 2023 breach exposed 200 million email addresses. Ireland's Data Protection Commission opened a formal GDPR investigation in April 2025 over how X uses EU user data to train Grok.

Worth knowing

X rewrote its Terms of Service in January 2026. Anything you type into Grok, prompts and outputs alike, now counts as your "Content." X is free to reuse it however it wants. There is no way to opt out of this specific clause.

Content moderation has thinned out since the 2022 acquisition. Research shows hate speech on the platform has grown. About 7 million monthly active US users left between 2022 and 2025, many heading to Bluesky (35 million users by April 2025) or Threads (350 million by May 2025). All data sits on US servers. There is no EU data residency option.