What is the term used for the hole in the iris of a lens?

The term used for the hole in the iris of a lens is referred to as the aperture. The aperture plays a crucial role in controlling the amount of light that passes through the lens and reaches the camera sensor or film. It is adjustable, allowing photographers to manipulate exposure and depth of field in their images. A wider aperture (a larger hole) allows more light in, which is beneficial in low-light situations, whereas a narrower aperture restricts light and increases the depth of field, making more of the image appear in focus. Understanding aperture is fundamental in photography, as it directly influences both the exposure and aesthetic quality of an image.