Aperture means to open the lens of the camera to let more light into the lens. Aperture is expressed in numbers, the average camera aperture goes from f/1.4 to f/22. The bigger the number the smaller the hole in the lens letting in less light. The smaller the number the larger the hole in the lens letting in more light.

How Aperture effects Exposure

As aperture controls the the amount of light that reaches the camera sensor therefore effecting the exposure of an photo. meaning that a wide aperture can lead to over exposure as there is too much light and a high aperture can lead to under exposure as there is too little light.

How Aperture effects Depth of Field

Depth of field is directly effected by Aperture the higher the aperture, for example f/22 the more background that’s in focus. For wider apertures it lets in more light meaning less of the background is in focus.