What factor is crucial in determining a monitor's resolution?

The crucial factor in determining a monitor's resolution is DPI (Dots Per Inch). DPI indicates the number of individual dots that can be placed in a linear inch of an image when printed or displayed. In the context of monitors, a higher DPI suggests that more pixels are packed into a given physical area, which translates effectively to better image clarity and detail. This density of pixels directly influences how sharp and clear images appear on the screen.

While frame rate plays a role in the fluidity of motion displayed on the screen, and aspect ratio describes the proportional relationship between the width and height of the display, these elements do not define resolution. Pixel size may refer to the physical dimensions of the individual pixels, but it is DPI that primarily establishes how many of these pixels can be displayed in a specific area, thus affecting the overall resolution of the monitor.