F/STOPS AND BLUR DEFINTION - apeture

main F/stops-
F/2
F/2.8
F/5.6
F/11
F/16
F/22

Aperture Blur-
The visual quality of the out-of-focus of a photograph used by a particular lens.

Use Manual on a camera.

Apeture is extremely important when taking a photograph as it can allow for a specific object or subject to be sharp and in focus where as the background would be out of focus