https://support.google.com/websearch?p=aimode

Google Search AI Mode is a Gemini-powered, conversational search experience that breaks down complex queries into subtopics to provide detailed summaries with inline citations. This user-activated feature supports multi-step follow-up questions, multimodal inputs, and is currently available to users over 18 in the US with specific account settings enabled. For more details, visit Google Support. Get AI-powered responses with AI Mode in Google Search