.NET remoting is a Microsoft technology designed for communication between distributed applications across different machines, facilitating interaction through remote objects and proxy mechanisms. It supports multiple communication protocols and offers two primary activation modes: single call and singleton, while emphasizing security through custom authentication and SSL. Although .NET remoting provides flexibility and performance, it has limitations in complexity and cross-platform support, prompting developers to consider newer alternatives like WCF and ASP.NET Web API for modern distributed applications.