In One Sentence
AI Search is a search experience where, in response to a user's question, generative AI (ChatGPT, Claude, Gemini, etc.) presents a direct answer plus citation URLs.
What does this look like in practice?
In a traditional Google search, searching "What is the fastest route from Tokyo to Osaka?" returns a list of links. The user had to click through promising articles and assemble information on their own.
By contrast, asking the same question in AI search (e.g. Perplexity) returns something like:
From Tokyo to Osaka, the (source: JR Central official). The actual flight time is shorter, but including airport access the total ends up roughly the same as the Shinkansen (source: X Airlines).