WHAT (Window Hotkey Activator Tool) is software used to manage and automate the activation of program windows in Windows through customized keyboard shortcuts. It allows you to set up hotkeys to switch between open windows, facilitating quick access to applications and background processes. WHAT is useful for those looking to increase productivity by organizing workflow through shortcuts without the need to use the mouse. The program features a simple interface where you can define, edit, and delete shortcuts quickly and effectively.