Which is better between static variable and Application variable?

Question

In my website http://www.hothelpdesk.com , I hope to set a global variable to store domain. so I can access the value in my code anywhere. I think both Method A and Method B can do that! In Method A, I use static variable HotHelpDesk.BLL.PublicPar.MyDomain, so I can access the value of HotHelpDesk.BLL.PublicPar.MyDomain in my code anywhere. In Method B, I use Application["MyDomain"], so I can also access the value of Application["MyDomain"] in my code anywhere. Could you tell me what different between static variable and Application variable? Could you tell me which one is better? Many thanks! //--------------------------Global.asax------------------------------------------ void Application_Start(object sender, EventArgs e) { // Method A HotHelpDesk.BLL.PublicPar.MyDomain = HotHelpDesk.BLL.Par.GetDomian(); // Method B Application["MyDomain"] = HotHelpDesk.BLL.PublicClass.GetDomian(); } //--------------------------Global.asax------------------------------------------ //--------------------------PublicPar.cs----------------------------------------- using System; using System.Data; using System.Configuration; using System.Web; namespace HotHelpDesk.BLL { public class PublicPar { public PublicPar() { } public static string MyDomain; public static string GetDomian() { string Full = HttpContext.Current.Request.Url.ToString(); string ToBoot = HttpContext.Current.Request.AppRelativeCurrentExecutionFilePath; ToBoot = ToBoot.Substring(2); Full = Full.Substring(0, Full.LastIndexOf(ToBoot)); return Full; } } } //--------------------------PublicPar.cs-----------------------------------------