The Azure SignalR Service is a fully managed service that handles the thousands of persistent connections, so your web server doesn't have to.
Instead of the client connecting directly to your App Service, they connect to the Azure SignalR Service. Your App Service only maintains a few small 'Server Connections' to the Azure service. This eliminates the memory and CPU burden of managing 100,000 WebSockets on your own hardware.
Because the Azure service acts as the central hub, you no longer need Sticky Sessions on your load balancer. Any request can land on any server instance, because the 'State' of the connection is managed by Azure, not by your local server's RAM.
Q: "How many connections can it handle?"
Architect Answer: "The Standard tier can handle **100,000 concurrent connections** and even more if you scale out the 'Units'. It is the enterprise solution for high-scale apps like real-time gaming, live auctions, or global stock tickers where you can't afford a single server failure to drop all your users."