What is Aperture?
Aperture refers to the opening of a lens’s diaphragm through which light passes. It is calibrated in f/stops and is displayed as numbers such as 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, etc.
The lower the aperture number (or F/Stop) gives you more exposure to light because they represent the larger aperture opening, while a higher f/stop will give you less exposure because they represent smaller apertures.
This may seem contradictory at first but will become clearer as you take pictures at varying apertures. Check your camera manual to learn how to set your camera for Aperture Priority, then try experimenting with changing the aperture and recognizing the effects different apertures will have on your image.
In this animation, Apalapse explains Aperture and how it interacts with the various parameters of photography.