Software developer can use System.Web.SessionState.HttpSessionState member SessionID which provides the unique session identifier for the current user as a string. Related TutorialsHow to configure session state to use cookies in ASP.NET How to disable session state management in ASP.NET How to manage the ASP.NET web service transaction option in C# How server-side validation works in ASP.NET 4.0 How to transfer information between pages in ASP.NET using a query string in VB.NET.