C#程序的主函数写[STA Thread] 属性是什么目的？（What is the purpose of the [STA Thread] attribute for the Main method of a C# program? ）

C#中,[STAThread]代表什么意思?如何用?

> Single Thread Apartment vs MultiThread Apartment?
 
Correct: With the STAThread attribute, you will be interacting with COM processes in a "Single Threading Apartment" model.   Without it, you will be interacting with COM processes in the "Multiple Threading Apartment" model.
 
> so why do I need it....or why would I want it at some point?
 
You may want to interact with a COM process in a MTA model for performance reasons.   You may want to interact with a COM process in a STA model because of a design requirement.   For example, to use the Windows clipboard (System.Windows.Forms.Clipboard) you must be calling from a thread running in a STA.   If the calling thread was started by your application you can set the ApartmentState (System.Threading.ApartmentState) before starting, but if you want to use the clipboard from your application's main thread, you need to use the System.STAThread attribute on your Main method.
 
> why does Main( ) only function as an entry point when it is declared static?
 
The simple answer is that is just the way that Microsoft designed the language.   One way you can look at this though, is there should only be 1 "instance" of your Main method - the main method has nothing to do with any specific instances of the class it is defined in, and should therefore be static.   In my opinion it might have been a good idea to give the Main method a property similar to a static contructor where it is executed once, and only once.   Anyway, because the Main method is static, you can execute your program without having to create any arbitrary objects.

单线程套间，简单来说所有对于单线程套间中对象的访问都是通过消息来传递的，所以同一时间只有一个线程能够访问单线程套间中的对象。