When you hit the shutter release button of your camera a hole opens up that allows your cameras image sensor to catch a glimpse of the scene you’re wanting to capture. The aperture that you set impacts the size of that hole. The larger the hole the more light that gets in – the smaller the hole the less light. Aperture is measured in ‘f-stops’.f/2.8, f/4, f/5.6,f/8,f/22 etc. Moving from one f-stop to the next doubles or halves the size of the amount of opening in your lens (and the amount of light getting through). Keep in mind that a change in shutter speed from one stop to the next doubles or halves the amount of light that gets in also – this means if you increase one and decrease the other you let the same amount of light in
Diagram from https://www.city-academy.com/news/what-is-aperture-in-photography/
below are photos taken with low to high apertures:
the middle photo below has been taken with a low aperture, resulting in a shallow depth of field, whearas the photos on either side have been taken with a high aperture, resulting in a deep depth of field.
all photos below have been taken with a low aperture, resulting in a shallow depth of field.
best photo:
This is the best photo because I have used a unique angle by placing the camera on the ground. Also, I have used the correct white balance to capture the orange and greens of leaves. I have used a low aperture to create a shallow depth of field, with only the leaves in the middle of the shot being in focus. I have used the standard aperture, shutter speed and ISO settings to create a balanced photo.
worst photo:
This is the worst photo because there is not much in the shot. I like it because it's very simple but some may find it boring.