Shutter speed is the amount of time the shutter (a flap or curtain covering the image sensor) is open to control the amount of light passing through the image sensor creating a photo. This displays how blurry or sharp your photo will come out as.
The first image is my best image because the shutter speed was very high which meant my picture came out very crisp and clean which is what I wanted. It makes the picture stand out and look very professional.The second photo is my worst image because the background isn't appealing, the ISO is too high which bleaches the photo and the aperture is too low which explains why it is blurry.