Aperture
The correct exposure depends on three main factors: aperture setting, exposure time and sensor sensitivity. These three camera factors adapt to the changing strength of the ambient light and thus ensure consistently good recordings in very different lighting conditions.
The aperture is a component within the lens that, among other things, limits the amount of incident light. There are fixed apertures and variable apertures. Fixed apertures always allow the same amount of light to pass through. They are therefore more suitable for indoor cameras that are confronted with constant light intensities. With fixed apertures, sensor sensitivity and exposure time alone must compensate for any fluctuations in light intensity that may occur.
Variable apertures provide an additional way to regulate the amount of incoming light by allowing them to be opened further or closed further. If it is very bright, it is advantageous to have the aperture closed very wide so that the light opening is small. Professionals call this a small aperture, although it's actually about the aperture opening. On the other hand, if it is darker, a large aperture is better, i.e. a wider aperture. For the variable aperture settings, a distinction can be made between automatically switching and manual apertures. Automatic apertures can be technically implemented in different ways, but basically all variants are very comfortable: the opening is always optimally adapted to the ambient light, sensor sensitivity and exposure time without any action on the part of the user.