This is the top portion of the shoulder from the backbone down to the top of the Picnic Shoulder, including the shoulder blade. It may be sold skin-on but is more commonly without skin
The term "butt" has nothing to do with the rear end of the pig, this is the front shoulder. Some say it was called "Boston Butt" because it was packed in a barrel called a "butt" but I think that's reaching.
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This is the boneless version of the Boston Butt, actually cut a bit different from the regular version. This cut is often rolled and secured with netting to provide a uniform roasting thickness.
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This is the pig version of the beef "7 bone steak", a slice from the Boston Butt. A boneless version is #1407.
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Cooking: This cut can be pan fried like pork chops, but
will have more flavor and be a little tougher.