What effect does increasing ISO have on a photograph?

Increasing the ISO setting on a camera makes the sensor more sensitive to light, which allows for better exposure in low light conditions. However, this increased sensitivity also leads to the introduction of noise or grain in the image. This noise manifests as random variations in color and brightness that can compromise the overall quality of the photograph. As the ISO setting is raised, particularly beyond 400, the likelihood and prominence of this noise increase, making it a critical consideration in low-light photography. While it can help capture an image in dim lighting, one must balance sensitivity with the potential degradation of image quality due to this added grain.