When our brains don't receive the visual information that we expect to see, it tends to creep us out. That's the effect that usually happens in photography and photo editing whenever a person's body is cropped at the joints. If we see an elbow but no forearm, we have a hard time filling in the missing details; the photo just ends up looking unsettling.
That's not to say that you should never crop at the joint. In some situations, that might be an intentional choice that's better suited for the particulars of your photo. But if you don't know what you're doing, it will look more like a mistake.
Every photo (and every person's body) is a little bit different, so there's no absolute rule for where you should crop every subject every single time. But this diagram offers some great guidelines, highlighting the best places to crop a subject's body in most situations.
Infographic by: companyfolders.com
That's not to say that you should never crop at the joint. In some situations, that might be an intentional choice that's better suited for the particulars of your photo. But if you don't know what you're doing, it will look more like a mistake.
Infographic by: companyfolders.com
