C# Definition:

private delegate int LowLevelKeyboardProc(int nCode,WindowsMessages wParam, [In] KBDLLHOOKSTRUCT lParam);

VB.NET Definition:

Private Delegate Function LowLevelKeyboardProc(ByVal nCode As Integer, ByVal wParam As WindowsMessages, <[In]> ByVal lParam As KBDLLHOOKSTRUCT) As Integer

User-Defined Types:

WindowsMessages the type of event. This will be WM_KEYDOWN, WM_KEYUP, WM_SYSKEYDOWN or WM_SYSKEYUP

KBDLLHOOKSTRUCT contains details of the key

Notes:

See SetWindowsHookEx, CallNextHookEx