Can any tell me why this error is coming while rebuilding the Project..... MySocket.obj : error LNK2019: unresolved external symbol _send referenced in function "long __cdecl ServerProc(struct HWND__ *,unsigned int,unsigned int,long)" (?ServerProc@@YAJPAUHWND__@@IIJ@Z) MySocket.obj : error LNK2019: unresolved external symbol _WSAStartup referenced in function "int __cdecl InitSocket(struct HWND__ *)" (?InitSocket@@YAHPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _gethostbyname referenced in function "void __cdecl GetLocalIP(struct HWND__ *)" (?GetLocalIP@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _gethostname referenced in function "void __cdecl GetLocalIP(struct HWND__ *)" (?GetLocalIP@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _connect referenced in function "void __cdecl OpenSocket(struct HWND__ *)" (?OpenSocket@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _inet_addr referenced in function "void __cdecl OpenSocket(struct HWND__ *)" (?OpenSocket@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _htons referenced in function "void __cdecl OpenSocket(struct HWND__ *)" (?OpenSocket@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _socket referenced in function "void __cdecl OpenSocket(struct HWND__ *)" (?OpenSocket@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _closesocket referenced in function "void __cdecl CloseSocket(struct HWND__ *)" (?CloseSocket@@YAXPAUHWND__@@@Z) MySocket.obj : error LNK2019: unresolved external symbol _accept referenced in function "unsigned long __cdecl StartListen(void *)" (?StartListen@@YAKPAX@Z) MySocket.obj : error LNK2019: unresolved external symbol _select referenced in function "unsigned long __cdecl StartListen(void *)" (?StartListen@@YAKPAX@Z) MySocket.obj : error LNK2019: unresolved external symbol ___WSAFDIsSet referenced in function "unsigned long __cdecl StartListen(void *)" (?StartListen@@YAKPAX@Z) MySocket.obj : error LNK2019: unresolved external symbol _listen referenced in function "unsigned long __cdecl StartListen(void *)" (?StartListen@@YAKPAX@Z) MySocket.obj : error LNK2019: unresolved external symbol _bind referenced in function "unsigned long __cdecl StartListen(void *)" (?StartListen@@YAKPAX@Z) MySocket.obj : error LNK2019: unresolved external symbol _recv referenced in function "unsigned long __cdecl ReadInBuffer(void *)" (?ReadInBuffer@@YAKPAX@