有人能解释互斥以及它是如何使用的吗?

我读了一些关于互斥的文档,但我得到的唯一想法仍然是,它有助于阻止线程访问已被另一个资源使用的资源。

我从代码片段中获取并执行了一个很好的代码:

#include <windows.h>
#include <process.h>
#include <iostream>
using namespace std;


BOOL FunctionToWriteToDatabase(HANDLE hMutex)
{
    DWORD dwWaitResult;
    // Request ownership of mutex.
    dwWaitResult = WaitForSingleObject(
    hMutex, // handle to mutex
    5000L); // five-second time-out interval
        switch (dwWaitResult)
        {
        // The thread got mutex ownership.
            case WAIT_OBJECT_0:
            __try
            {
                // Write to the database.
            }
            __finally {
            // Release ownership of the mutex object.
            if (! ReleaseMutex(hMutex)) {
            // Deal with error.
        }
            break;
        }
            // Cannot get mutex ownership due to time-out.
            case WAIT_TIMEOUT:
            return FALSE;
            // Got ownership of the abandoned mutex object.
            case WAIT_ABANDONED:
            return FALSE;
        }
    return TRUE;
}

void main()
{
    HANDLE hMutex;

    hMutex=CreateMutex(NULL,FALSE,"MutexExample");

    if (hMutex == NULL)
    {
        printf("CreateMutex error: %d\n", GetLastError() );
    }
    else if ( GetLastError() == ERROR_ALREADY_EXISTS )
        printf("CreateMutex opened existing mutex\n");

    else
        printf("CreateMutex created new mutex\n");

}

但我不明白的是,线程在哪里,共享资源在哪里?有人能解释一下或者提供一个更好的文章或者文件吗?