asynchronous event(An event whose handler runs in a different processing thread from the action that raised the event. The event handler and the action are processed simultaneously)
asynchronous pattern(A core technology in the .NET Framework which provides an efficient model to manage asynchronous operations and a consistent programming model)
asynchronous postback(In ASP.NET, the process of sending Web page data (plus viewstate and other necessary metadata) from the browser to the server without a complete postback and without blocking the user from continuing to work in the page. Asynchronous postbacks are an important feature of AJAX technology)