VBlank (Vertical Blank) refers to the brief interval when a CRT monitor's electron beam returns from the bottom to the top of the screen to begin drawing the next frame. On Amiga systems, this occurs at 50Hz for PAL or 60Hz for NTSC, and the custom chipset can generate hardware interrupts at this precise moment. Programmers utilize VBlank interrupts to synchronize graphics updates, ensuring smooth animation without screen tearing and creating stable timing mechanisms for games and demos.