In its simplest form, tripe is the lining from the stomach (or stomachs) of a domesticated animal. Most often the first three stomachs of a cow or an ox are used. When the first of the bovine’s stomach is used, it is called blanket tripe (due to its appearance); when the second—and usually most coveted—is prepared, it is known as honeycomb tripe; and when it is the third stomach, it is called bible or book tripe. The last stomach of a cow or ox is rarely used because of its glandular texture. Tripe dishes are also sometimes made with a pig, sheep, goat, or even deer stomach.
"Diana Kennedy writes that smooth tripe, the kind Mexican cooks call callo, or toalla in the Yucatan ("towel" tripe, on account of its relative smoothness), is best. Samiljan calls it leaf tripe, the lining from one of a cow's four stomachs that's smaller than the large organ where the honeycomb stuff comes from, meaning there's less of it to go around."