There are 2 ways that we can control how much light hits our digital sensor
Aperture and Shutter speed.
In this class I will be teaching you about your lens's aperture.
What it is, how to use it to control your exposure and the quality of your image and also how to control your depth of field so you have control over the sharpness of particular parts of your photograph.

What is Aperture?: Aperture means a hole in something, hole inside your lens that you can make larger or smaller to let more or less light through.  It is actually a diaphragm with a number of blades that rotate to close or open the aperture. It works in a similar way to your eye.

The primary purpose of your aperture is to let more or less light through to your sensor to make your photo brighter or darker.
Apertures are displayed with an F in front of the number (this is why some people call them F stop)
The actual number is a measure of the focal length of your lens divided by the diameter of the hole. So it is technically a fraction (eg. 1/5.6, 1/8)



Content Source:

https://www.skillshare.com/classes/Understanding-Aperture-The-Logical-Way-to-Control-Exposure-and-Depth-of-Field/1095252423