Using the Windows SetWindowsHookEx function with the WH_KEYBOARD_LL hook (low-level global hook) allows a C program to monitor keyboard input system-wide without needing to poll. This is the most common method for software keyloggers.
This is the simplest method where the program runs in an infinite loop, constantly checking the state of every key on the keyboard to see if it’s currently being pressed. Windows Hooking ( SetWindowsHookEx c keylogger
The Windows operating system manages input via a messaging system. When a user presses a key, the hardware driver generates an interrupt, which Windows translates into a message (such as WM_KEYDOWN ) and sends to the message queue of the active window. the hardware driver generates an interrupt
