In a late-night announcement, X owner Elon Musk unveiled the new Grok 4 chatbot. Here's everything you need to know about it.

Elon Musk’s live demo of Grok 4, the latest big-ticket model from his AI startup, began with high-intensity music, claims of a “ludicrous rate of progress,” and a lot of chatter on X about Grok’s scandal-filled week.

A few weeks ago, while comparing language proficiency in essays written by ChatGPT with that in essays by human authors, I had an aha! moment. I realized that I was comparing a single voice—that of the large language model,