ISO originally stood for International Organization for Standardization, but in digital photography, it refers to your camera sensor’s sensitivity to light. Higher ISO numbers mean more sensitivity to light.

Film ISO was a physical property of the film emulsion, while digital ISO is achieved through amplifying the sensor’s signal. This is why digital cameras can change ISO settings between shots.

Not necessarily. While lower ISOs provide better image quality, sometimes you need higher ISO for proper exposure. It’s better to have a slightly noisy sharp photo than a blurry one.

ISO is one of the three pillars of exposure (along with aperture and shutter speed). Doubling the ISO (e.g., from 400 to 800) doubles the exposure, equivalent to opening your aperture one stop or slowing your shutter speed by one stop.

This varies by camera model and personal preference. Modern full-frame cameras often produce acceptable results up to ISO 6400-12800, while smaller sensors may be limited to ISO 1600-3200.

Yes, modern noise reduction software like DxO, Topaz DeNoise AI, or built-in camera processing can significantly reduce noise while preserving detail.

Auto ISO automatically adjusts sensitivity based on your aperture and shutter speed settings. It’s useful for changing lighting conditions, but manual control gives you more creative control.

Larger sensors generally perform better at high ISOs because they have larger photosites (pixels) that can gather more light, resulting in less noise.