regarding [ThreadStatic()] c#

what is the meaning of [ThreadStatic()]

i got a piece of code and i found [ThreadStatic()] is used there what does it mean....when to use [ThreadStatic()]

public class Contex开发者_开发问答t
{
[ThreadStatic()]
private static Context _Context = null;

private HttpContext _HttpContext = null;

public Context()
{
    _HttpContext = HttpContext.Current;
}

public static Context Current
{
    if(_Context == null || 
       _HttpContext != _HttpContext.Current)
    {
        _Context = new Context();
    }
    return _Context;
}
}

From MSDN:

Indicates that the value of a static field is unique for each thread.

Read these:

• A tale of two techniques: The [ThreadStatic] Attribute and System.Web.HttpContext.Current.Items
• CallContext vs ThreadStatic
• MSDN Blog: Are you familiar with [ThreadStatic]?
• How well do you understand ThreadStatic?

From the documentation:

Indicates that the value of a static field is unique for each thread.

In your code _Context is static, but it is different for each thread.

If you have a background in more native programming, think of these as a semi-equivalent of Thread Local Storage.