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 and often without bone. If boneless it may be rolled up and secured with netting.
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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