Understanding Aperture

What is aperture?  Well.....

Techanchally, aperture is the size of the opening in the lens when a picture is taken. The aperture in the camera is like an eye. The pupil in an eye gets bigger when it gets dark to let more light in. When it gets brighter, the pupil gets smaller to let less light in. Well, same thing happens with aperture in a camera. The lens gets bigger to let more light in and it gets smaller to block more light out. Visually, aperture allows the photo to have blur. 

This picture has a low aperture number and so it has blur. Blur lets you focus easier on a subject.

 This picture has a high aperture number and so it's much clearer. 

Aperture is a very important part in the exposure triangle. The exposure triangle contains of 3 items, aperture, shutter speed, and ISO. If you change one thing, then everything else changes also.  If you change aperture, but don't change your shutter speed, then there is not enough light coming in through the camera. If there is not enough light coming through the camera, then the picture will not turn out the way you want. Everything works together to make the perfect photo.