ISO is one of the three pillars of photography, along with shutter speed and aperture, and it has a major effect on your images. ISO refers to the sensitivity of your cameras sensor to light. A lower ISO value means less sensitivity to light, while a higher ISO means more sensitivity. Every camera has a range of ISO values, with the lowest number identified as the base ISO (usually around 100) . From there, each ISO value on the scale is typically double the previous one, such as 100, 200, 400, 800, 1600.

When you use low ISO values such as 300 and lower, generally the result is a higher quality photo. Bright conditions, like shooting outdoors on a sunny day, benefit from lower values. Landscape photography, for example, is very well-suited to low ISO values. Another benefit of a low ISO is the lack of graininess or noise in your photos. Every time you raise the ISO, it results in a similar decrease in image quality, which is why photos shot with a high ISO can produce an unwanted grainy effect.

In dark locations, you can increase the shutter speed to make camera shake and subject blurring less likely to occur. In bright locations, you can reduce the ISO Sensitivity to make the amount of noise smaller. ISO AUTO is a setting in which the camera will automatically make these settings.

In summary, ISO is a camera setting that adjusts the sensitivity of your cameras sensor to light. It is one of the three pillars of photography and plays an essential role in the quality of your photos. A lower ISO value means less sensitivity to light, while a higher ISO means more sensitivity. Low ISO values generally result in higher quality photos with less graininess or noise.