Alphabet said it is rolling out its artificial-intelligence chatbot, Bard, in Europe and Brazil on Thursday, the product's biggest expansion since its February launch and pitting it against Microsoft-backed rival ChatGPT.... Bard and ChatGPT are human-sounding programs that use generative artificial intelligence to hold conversations with users and answer myriad prompts.... Earlier this week, billionaire Elon Musk also launched his long-teased artificial-intelligence startup xAI, whose team in