Global.asax.cs文件里的内容,

Global.asax.cs文件里的内容,
小弟初学,这个文件里面的东西都分表是做什么的,可以在里面加点什么内容,能干点什么呢?
protected void Application_Start(Object sender,EventArgs e)
{
}
protected void Session_Start(Object sender,EventArgs e)
{
}
protected void Application_BeginRequest(Object sender,EventArgs e)
{
}
protected void Application_EndRequest(Object sender,EventArgs e)
{
}
protected void Application_AuthenticateRequest(Object sender,EventArgs e)
{
}
protected void Application_Error(Object sender,EventArgs e)
{
}
protected void Session_End(Object sender,EventArgs e)
{
}
protected void Application_End(Object sender,EventArgs e)
{
}