You request static assets from a CDN and your request hits a "lambda" function on the edge. It inspects your user agent and decides to send you mobile-optimized

You request static assets from a CDN and your request hits a "lambda" function on the edge. It inspects your user agent and decides to send you mobile-optimized assets. It's largely about latencies. Doing certain request(and response!) processing closer to the client, along with potential data locality benefits, you can get responses back faster and more efficiently.