Many social websites, and web-based applications, have a notification process where the server sends a signal back to the browser, informing that particular user that there is a message. "You've got mail," as America On-Line used to say it. Consider the picture below, from Twitter, which shows that I have one new notification. That number increments automatically when a new notification arrives, without having to reload the full page. How does that work? Well, this blog post doesn't try to answer that directly. In fact, it is simply a collection of notes pointing out how to use Microsoft's SignalR technology to achieve this.